I don't remember who asked for the part number for the HP 85 printer drive belt but I finally dug out my service manual and found the numbers. There are two belts in the printer. One drives the carriage and is PN 1500-0529. The other drives the paper advance and is PN 1500-0572. If one is bad you should go ahead and replace both. During the week you can call HP's automated ordering line at 1-800-227-8164 and order them if they're still available. Let me know if these are still available and what they cost. If you can't get them, let me know and I'll open up one of my 85s and measure the belts and to to match them up with something from Small Parts Inc or one of the other companies.