[NutmegCarrera]

For what it's worth:
I just finished replacing the window regulators (996 C4S Coupe in my case).
The first one went fine. I disconnected battery power because I was worried about messing with the airbag, etc....
Got it all back together, and then put power back on - and ran window up and down with no issues.
After doing all that - opened the door, and the 'auto down' feature worked to make clearance for the roof seal.

Went to work on the passenger side next. Figured out that I do NOT need to mess with the airbag - so - left the battery connected.
Finished everything up - and then tried opening the door. No auto-down. Tried using both inside and outside doors - no luck.
THEN, I REALIZED - I had not cut the battery power.
Went ahead and pulled the battery for a few minutes (took negative lead off). Waited a few minutes - turning the ignition on and that sort of thing...
Reconnected the battery, and turned ignition on.
Ran the window all the way down and then all the way up. Viola - all trained. Auto down was now working.

By the way-
I purchased the URO Parts regulators. There is a secondary 'stop limit' plug in the lower position. Think this is used to differentiate Boxster from Carrera. You need to pull that piece out. Also better make sure to mark location of the lower bolts (from bottom of door frame) for crosswise location before removing the old one. Same for window position relative to the regulator.
And, BONUS POINTS: Measure the gap between the back edge of the door window compared to the rear 1/4 glass before taking it all apart. This is how you check to make sure you've got the glass re-installed in the forward/backward location correctly.

You really should look at a few youtube vid's before attempting. Find what makes sense to you out of multiple. There's a norwegian guy with a really good series of videos, and another guy with a cabriolet that does a nice job with his video.

Finally - there is a 'repair' solution manufactured and sold by EPS European Parts Solution. Basically like a bicycle cable ferrule to replace the plastic deal that breaks near the pulley (where it bolts to the regulator motor). You can buy the parts - but you have to go search for their instructions. I tried this first. Thought - hey, why not replace the weak link and make it better. I found them for $70/ea. (And found the complete regulators for $125/ea).
Long story - don't do it. I tried, fought with it for a couple hours. Made a jig to hold the regulator so I could get spring tension in it again - all after destroying some other plastic bits around the regulator per EPS's instructions. No way in the world am I seeing how you're gonna 'gain' all the slack you need to get that cable back together.
Unless somebody's found the right way to do this - avoid this fix like the plague. Absolutely miserable.


Good luck - in the event that anybody finds my ramblings useful.
(My car is 21 yrs old, and started acting like this 1-1/2 year back. Very low miles. Think it's more of an age thing. I think they just get brittle and break from age.