It seem to me that if you are seeing little to no movement of the fork and the pedal is stuck to the floor then you have a linkage problem. The clutch would return without a return spring. The return spring only holds the throw out off of the fingers so its not spinning all the time. I am assuming that this is a purely mechanical clutch linkage. It almost sounds like a hydrolic that needs to be bled. If teh disk was installed backwards then it would not engage at all period. If someone turned down the flywheel to much it will move it away from teh throh out bearing but that is a long shot. My guess is they monkeyed with the linkage more than they are admiting. When you said the clutch only lasted 30 miles. What was wrong with it. Was it slipping or was it that it would not disengauge. If it was slipping it was probable adjusted wrong and it will burn up real quick. If it wouldnt release my guess is the linkage broke or bent somewhere.