1988 YJ Transmission grinding while clutch is depressed and shifting between 1st, 2nd, and 3rd gears. Its hard to explain but once transmission (it is the original transmission) heats up a bit I'll get a grinding noise when pressing in the clutch to shift gears. Even if I move it to neutral with the clutch depressed it grinds. Letting off of the clutch solves the issue. Sometime shifting between 1-3 gears has the grinding issue as well. Not too difficult to shift, it seems to go right into gear, but its a fairly rough sound. Any ideas?