I've been scratching my head for years trying to figure out a solution. two things I came up with, and they seemed to help, was to drill and tap out the other bosses on the outer sheave. Then use 3 bolts and lock nuts to adjust belt deflection. You would still have a free hole to screw in the tool to spread the clutch for belt removal.
I didn't do this specifically for inner sheave wear, it was more so the two sheaves would sit square rather than slightly cocked on take off with just one bolt spreading the sheaves. I don't know if the secondary would need to be rebalanced after this mod, but I had it done to be on the safe side.
I have a pic around somewhere showing the mod.
The other thing I tried was to trace out and cut a washer out of a milk jug ( poor mans delrin washer) the same dimensions as the washer and put between the sheave and the washer. That seemed to work also.
