The actual dimensions of a genuine Sonifex Micro HS main drive belt are 6mm x 340mm. If allowed to form a circle at rest I would say the diameter is 110mm.
Thanks to all. I have a feeling that it is the pinch wheel that is not engaging with the tape in play/fast forward mode that is the problem after all. I can't find the the adujustment for this a s the manual does not show a picture. Stuart