I have two M800s from long ago; great decks. Once upon a time
Aiwa had a repair facility in San Antonio, TX, but I can't seem to
locate them anymore since Aiwa "merged" with Sony. I might suggest communicating with www.mcmelectronics.com, they are
a big electronics supply firm and seem to carry belts for many kinds
of equipment. Their catalog is extensive.
N. Moretti
May 2008