So I have a CD50 that plays perfectly, but the tray seems to jam between the open/close process and the raising of the CD spindle process.  I have opened it and replaced the belt an added some lithium grease to the gears.  I also swapped out the largest gear, which was worn at the point where the indexing pin moves in and out (I have a few used parts from another broken unit).  I have had it disassembled and reassembled, and the gears still catch and stick at the same transition point.  If I help the gears through that specific point with my finger everything works as expected. My question is this: shy of removing, cleaning, and reinstalling all of the gears, is there another way to diagnose this problem?  Would a slipping belt cause this problem?  If not, something else?