Serving the universe
You can try Projector-Recorder belt if you have an idea of the size, shape, etc.
http://www.russellind.com/prbline/prblinecom_.htm#
Found an old post with the belt dimensions (thanks to GC) http://jinglemad.com/forum/index.php?p=/discussion/comment/51329#Comment_51329
So maybe one of these will do the job Belt 13 from here http://www.turntabledrivebelts.com/ or http://www.signalsuk.com/Shop/Audio/Belt-Capstan/9201-Flat-Capstan-Belt-339mm.html
just dug out my manual, belt is quoted as 104mm/6mm/1mm
Presumably 104mm is diameter if laid out in a circle, so π x 104 = 326.5mm belt length.