I thought I would provide an update: Winger was able to find a brass gear at Hobby Town made by Vetta (VTAS01038). It is a MO.6 Pinion Gear 17T. Had to bore out the shaft to fit on axle. Installed the gear and the engine runs as smooth as new. Thanks to Winger for tracking this down at the store near him; my store did not have that gear in stock.
Hope none of you with Coors engines has this problem, but if you do there is an acceptable fix.