I sent it into a shop since I didn't have the bandwidth to pull the transmission myself right now (my 911's transmission is still on my workbench). They said that I was down to the rivets on the clutch, so they replaced the whole thing: Clutch, dual-mass flywheel, fork, post, slave cylinder (again) etc. I got it back, and took my wife out to dinner in it. It worked great! When we got back, I couldn't get the car into first gear.
It seemed like there may have been some air in the hydraulics. So I figured that I'd bleed it and be good to go. So I took out my vacuum bleeder, put the pedal to the floor and lo and behold, bubbles came out of the slave cylinder. And more bubbles. And more bubbles. I've since run about 3 liters of hydraulic fluid through the system, and I'm still getting tons of bubbles. I'm making sure to keep the fluid above the "add" mark in the reservoir.
I'm not seeing any leaks. The master cylinder is dry, as is the area up by the reservoir. I'm keeping the fluid above the "add" mark when bleeding. When I close the bleeder valve I'm not getting any bubbles, so it's not like the bubbles are leaking past the bleeder nipple.
Any ideas?