WTB: part #s 15-933 and 15-939
 

As you can see on page 50 of the pdf at this link, these are parts related to the AC idler pulley:

http://www.rotaryart.uk.com/acatalog...CatalogLHD.pdf

It is the "COLLAR, COMP.BRKT" and ""SHAFT, PULLEY".

Thanks!

That works! Thanks, Shady!