If you just need the belt, take the old one to any auto parts store for
If you need other parts, you would be better off replacing it. Another
company made the openers for Automatic Doorman under private label, but
at the moment I can't think of which company it was. However, most of
the parts would be obsolete thru a opener manufacturer.
I don't really know about your brand of equipment, but you can try
looking for the part here http://www.aaaremotes.com . They seem to carry
almost everything out there.