In an effort to keep this all straight in my head, I put together this quick diagram. Does it look right?
I think I might have 1/2 and 3/4 backwards... I can check when I get home.

http://forums.pelicanparts.com/uploa...1409064947.jpg

There's a good chance the reason you still can't get into 1st is because a couple of those synchro teeth are jammed up in your slider blocking the motion of the gear.

Once I lay the transmission on its side, I was able to wiggle the shafts out easily.

Here is 1/2 in all its glory.
First, here it is in second gear engaged. Everything slides in nicely. Looking in the gap towards first, I don't see any issues but the 4 missing teeth.
http://forums.pelicanparts.com/uploa...1409093408.jpg

However she still won't slide into first gear position. This is as far as she moves. The blockage seems to be even - it doesn't seem to move further in on one side or the other. I can't see what could be in the way. Ideas?
http://forums.pelicanparts.com/uploa...1409093508.jpg

After disassembling the 1/2 shaft, I found I still can't pop the operating sleeve over 1st, although it will slide over 2nd.

I compared 1st and 2nd carefully. The synchronizer ring on 2nd compresses and the thrust block and break band inside it move a little when I mesh into 2nd. The synchronizer ring on 1st won't compress at all, so the operating sleeve can't get over it. Its break band and thrust block are immobile.

I tried removing the circlip on 1st, but could only get it part way off. After messing with this a few times, I discovered I had somehow made the synchronizer ring compressible again, and now the operating sleeve can engage with it.

I presume something is broken inside, so I'm going to keep trying to get that circlip free.

There are circlip specific pliers you can grab at Sears that will get it right off for you.
Sounds like the broken teeth allowed the brake band and stop assembly able to stack up behind each other stopping the compression of the synchro.

Got the circlip off.
The synchronizer ring had been rotated too far in one direction, and had even jammed the inward-facing thrust block at an angle. This is why the ring couldn't compress, and the circlip was so tight.

My rookie analysis is that the driver attempted a downshift and nearly took it all the way into first gear. This put so much pressure on the synchro ring that it jammed, and probably took off a few dog teeth.

I'm going to examine 2nd's synchronizer as well, once I get some better circlip pliers. I am thinking I will need new:
1) 1st Gear
2) 1st Gear Synch Ring, Circlip, Brake Band, and Thrust Block
3) 2nd Gear Synch Ring ("While I'm in there")

I'm not sure if I want to pull 3/4 off their shafts, as they have been working just fine.
If I was doing this at the track and needed to drive home, I could probably reassemble and drive it for a while, but I suspect it is only a matter of time now until the 1st gear synchro does worse than jam.

Do you think I really need new brake band, anchor/thrust block, and stop block? I'll look at them carefully, but unlike synchro's I don't know how to identify damage or wear.

you don't need 1st gear, just the syncro teeth. you should replace both syncros and the shift sleeve together for best results. with all the trauma to the 1st band and dogs, perhaps new parts are in order there too.

What John Walker said.

For general educational reference, here is what I'm looking at so far part-wise.
The items in green are what JW recommends I replace seeing as I am replacing their matching part on 1st gear. I plan to inspect all the parts for 1st and 2nd carefully tomorrow night.

http://forums.pelicanparts.com/uploa...1409231785.jpg

Oh, and what is the best thing for cleaning these up? For now I've been bagging everything to keep it clean. Should I just wipe them with my shop towel, or should I use WD40 or something? I understand I don't want to de-oil them or they would rust.

no swepco if you want it to shift easily.

JW, what fluid would you recommend? I see another person recommended Kendall.

I would just leave them in the bags until you are ready to reassemble. I like to use CRC Chlorinated Brake Cleaner to degrease (red spray can). Capture the residue and dispose of at your town's haz waste day.

Some of the bearings that are pressed on the shafts are supposed to go on clean and dry, so you'll have to degrease those. See instructions in Pete Z.'s tutorial:
Porsche Wiki

Don't forget new lock washers for the bearing retainer plates, looks like you were about to lose one of those nuts.

Mark

kendall.

I presume this is our host's "Kendall 80W-90 GL-5 NS-MP Hypoid Gear Oil". It is cheaper too!

Can anyone recommend the best way to get the dog tooth gear off? I am reading about a factory tool and a puller, but don't see it on PP.

Pelican calls them syncro hub removal tools. It looks like you smack it.

The factory tools use a puller. See here:
How-To: Porsche 915 Transmission Repair Tutorial Part 4 - Porsche Wiki

New dog teeth are pressed into place.

On mine, I bought the new parts and a local independent shop that I've paid to do other work was kind enough to remove my old dog teeth and press in the new ones for free.

Mark

that's the old tool. the new one is two plates that bolt around the dog teeth and you press it off. maybe a local porsche shop has one.

Parts are ordered! Now its time to sit back and clean things for a few days.

Parts arrive today! I need to determine what sort of sealant to use on on the gaskets - preferably something I can find locally so I can put this together this week.

I read some references to Copper Spray. Is this the stuff?

This is the recommended stuff (Curil-T) in the Wiki rebuild site. Non hardening, used it on my 915, works great. Too bad you didn't mention this when ordering parts, as you would have it by now. LOL

Porsche 911 (1974-1989) - Engine Rebuilding Kits, Tools, and Supplies - Page 3

Found this post.

So I think I'll use copper spray. Apparently a variety of things work (shocker).

Gears are pressed! The local gurus (who had a lot of 915s around the shop) said that 2nd gear dog teeth seemed in fine shape, and didn't need replacement.
The big challenge was putting the gear assemblies back together.

Putting in the gear circlip is a challenge every man must face on his own. In the case of 2nd gear, the synchro ring would not stay seated. I would compress it into place, but unless I held it, it would pop out while I was trying to wrestle the circlip in. After many minutes of struggling, I came upon a genius solution.

Behold - the latest tool for any 915 assembler's arsenal! It needs a fancy name. I nominate "Zipperoo".
I will be selling them for only $15 plus shipping. Available in yellow, green, or blue colors. Orange costs extra.

http://forums.pelicanparts.com/uploa...1409790770.jpg

Align the Zipperoo around the synchro ring before placing it into the gear. Compress the ring with one hand while tightening the Zipperoo with the other hand. Continue until the ring remains compressed enough to lie in the dog teeth without popping out. Then insert the circlip (sorry, no tool to help there). Finally remove the Zipperoo by pulling on the special tab. If you accidentally remove the Zipperoo before finishing with the circlip, you will need a new one - it is nearly impossible to force the ring into an already tightened Zipperoo. Buy an extra one just in case!

We cannot accept returns of used Zipperoos, and reselling after use is strictly prohibited by international law.

Quick question - is this new synchro ring OK? The synchro for 2nd gear was uniformly coated, while this one for 1st had bare areas in the middle.
http://forums.pelicanparts.com/uploa...1409792037.jpg

looks like stains. are there chunks gone or is it smooth? be sure to orient the 1st brake band properly. with the gap at the top, the long side is to the left.
there is a measurement on the installed syncros. 1st/2nd should be 86.37mm plus/minus 0.17mm. measured with a caliper or micrometer at the highest point. 3/4/5 is 76.3mm plus/minus 0.18mm.

It is very hard to tell visually if they are stains or not. I ran my fingernails over them and the spots feel less coarse than the rest of the ring, almost as though the coating was not applied evenly, or was rubbed off some. The variance is fairly low. There are about 10 spots with the odd color, of which the ones in the picture are the largest. The 2nd gear ring was perfectly uniform in color.
I have already installed it onto the gear. I'd really hate to send it back and get a new one if the issue is minor, but of course doing it twice is worse.

I have an English micrometer, so here are the conversions:
Desired 3.400 inches +/- 0.007
On 1st gear the diameter is exactly 3.400 inches as desired. On 2nd gear, it varies slightly depending on where I measure. 3.400 at the largest, and as low as 3.390. Both rings are new. Maybe I can remove 2nd gear's ring and file something somewhere to allow it to expand further?

Who manufactured your synchros?

The rings are Rauch & Spiegel, from our host here.

Not a fan. I wouldn't put anything but OEM synchros, sliders and dog teeth in a 901 or 915. R&S tolerances and QC are all over the place.

So basically I have to send back new parts because PP supplied poor quality items?

This is looking like a major pain.

So what do you guys think? Should the spotty ring be returned? Should I file away the other to try to get it into tolerance, our return it as well?

I wouldn't risk it, return them. Matt knows what he's doing.

PP customer service was very nice and I am returning the defective parts and ordering new OEM replacements. It will take a little while to get here, but I think it is worth having the best parts.

Pelican generally has excellent customer service. I hate to badmouth anything our host sells, but the R&S stuff is being widely distributed through one of the major wholesale suppliers too. A lot of shops and owners think they can save a buck with the stuff, but it's just not up to OEM standards. This holds true of their G50 stuff as well. I've seen G50 synchros that dropped so far down onto the cone that they measured as "worn out" before they were even installed.

Parts take soooo long to arrive. Time to clean the engine bay and maybe do that valve timing.

1st gear synchro is here. 2nd should be coming in tomorrow!

Meanwhile, I did a backside method valve timing!

That's a nice trick. Please share the method.

Or do you mean valve adjustment?

Whoops, meant adjustment.

Synchro rings arrived and the two gears are assembled. Tomorrow I put together the shafts and reassemble. I don't have an engine stand, so I'm not sure about the best way to hold the transmission while I torque the big nuts. I also don't have the locking tool.

When I removed the nuts, I put the transmission in two gears at once. Can I do the same thing when I am torquing the nuts back on? Also, can I mount the transmission onto the engine (its out of the car) and use that to keep the transmission stable while I torque the nuts?

Then I'd take it back out of the two gears before I put the end cap on. Thanks for all your help everyone!