Several weeks ago a customer purchased a couple of rubber tracks from us for their Bobcat 331 excavator. We ran the serial number for an idler they needed but we couldnt come up with anything. The serial number came up with a steel tracked machine so we went out to the site to take a look.
The idler was completely shot and would have cost a fortune to rebuild. We measured the diameter of the wheel and came up with a nifty solution. Although the new idler arms were much bigger (see below) we were able to pin those off and pin the old arms on to the new idler wheel.
So if you're coming across this issue you might want to give it a try.