I just finished tearing my STS RS12 down, and found the front seal all distorted! That, I'm sure was causing my tuning problems. The bearings themselfs feel fine, but I took out the seal from the new bearing I have, and we will give it a try again.
When I broke this in, it took needle changes very well, quick to respond, but once on the track, and had a few hot laps on it, that's when the problems happened, SOOOO check your front bearing seal.
Also, I found the the piston has left a mark on the backing plate, where the relief is at. The piston shows no sign of damage, but with a tap dance on the backing plate, you know somehing is wrong.I do not know if CRC will do anything about this, but it would not hurt to ask if they have run into this before.
Smitty