[Walt Fricke]

Eric - did you use anti-sieze?

I used to have the feeling you have on my Beetle VW engines, but never on the 911. The plugs (modestly lubricated) just go in, bottom, and get that extra yank to be sure they are seated and going to stay put.

I usually install the plugs using a short rubber hose which just fits (but tightly) over the ceramic. Helps me locate the hole and get the plug started. Normally I can spin the plug down to its seat this way, so the wrench only turns a little to get some torque. Magnetic plug holders should work like this too.

If you are worried, why not use a thread chaser for the holes which seem odd? You can take an old spark plug, cut maybe 4 slots in its threads, and run it in (with lubrication) and back out. The slots should cut any small burring, and also keep the bits in place.