capt.ron,
You're welcome.
After looking at the parts drawing, I suspected it would be the left hand 10-1526 small gear. There are basically three sources for parts.
Someone on this list or on the Yahoo list.
Clausing.
eBay. Individual QCGB gears seldom show up (generally too little call for them so not worth the time to write an ad) but find the several sellers specializing in Atlas pieces and write and ask them whether they have any gearbox individual parts.
Robert D.