Suggestions for repairing HP tape drive capstans?

I have a number of HP QIC tape drive units -- I think it's 2 off 9142, 3 off 9144 (1 3-board, the other 2 are single-board) and a 9145 [1] all with hte same problem. The rubber capstan has turend to goo. [1] There's a darn 68000 processor in that drive, unlike the 68B09s in the other units. Eeek! The capstan is a rubber 'tyre' on a metal hub, the latter being glued to the motor spidnle. The diameter of the hub is around 12mm (but I wil measure that accurately) and the overall diameter of the tyre is perhaps 18mm (it's going to be hard to measure, sure the fact I don't have a solid one :-() Anyway, does anyone have any suggestions as to suitable material that I can obtain in the UK to repair this? Assume as ever I have a reasonable workshop and am not affraid to pull the drives to bits :-) -tony