Re: drive cluch
If we are talking primary clutch on the motor, I have never seen a shaft worn enough to cause the need for replacement. The bushings go bad long before they hurt the shaft. Sounds like one of the bushings is binding or maybe a bad spring. If the bushings were replaced I might question if they were damaged during the install, if they are ok check weights and rollers. Inspect those items while on the machine. If you have a puller, pull the clutch and take the lid off and check these points. Just make sure you get it back on in the same location you took it off... does't hurt to mark lid and movable sheave with a magic marker. The lid and movable should slide freely up and down the shaft with no side movement; if excesive side movement it maybe binding and your rebuilder didn't replace the bushings. Inspect the weights and their rollers. They should turn freely but not be sloppy on their pivots.
If you are talking secondary clutch you driven spring is likely bad, replace making sure to note which whole in the helix it was in and preload it 1/3 of a turn.