Hi NormK,
Yes it can be a pain in the rear end getting the circlip off but they do have pliers that are longer than normal so you can get to it.
The shaft usually wears because of the heat transfer when driving the nylon and damaging the spline, which causes it to scallop and not connect properly with the clutch drum.
We used to run longer than the normal length of nylon and also a larger gauge which caused the clutches to wear (also had to replace the clutch springs) a bit quicker and also damage the shafts which we rotated till we had to replace them which took quite a while before we had to do it.
This is the large clutch shoe which we have stock of
CLICK HERE NOTE:
The parts list have been uploaded to the spare parts area