Secondary clutch shims

I just installed a new Comet primary clutch. I’m working on the alignment and need a thinner shim(s). The original setup had two of the stock 0.060" shims on the shaft for the secondary clutch but this made the belt ride on the outer sheave of the primary. I removed one, but the belt was still riding on the outer primary sheave. Removing both has the belt riding on the primary’s inner sheave.

I need to locate a source for thinner shims, a 0.030" looks like it would do the trick. Any idea where I can locate thinner shims? The factory shims are all 0.060". I’ve been searching here and on Google to no avail.