I have two marantz tape / casette drives here that both need the drive belts replaced. 1) Marantz SD-53 (single deck - around 1995) Single belt. 2) Marantz SD-64 (digital monitioring - single deck) Two Belts. The problem is I'm unsure of exactly what size belts I need to buy for each tape drive. The SD-53 looks easy to install but the SD-64 I'll probably need instructions or help on installing that one as I haven't figured out exactly where the bels go as its alot more complicated. If anybody can help with belt sized needed, as well as installation instructions / service manuals pdf etc that would also be great.