Hi
Depends on what the problem is, they are a simple system. I am not 100% on the early ones but all the later ones are the same, should be a disk on the engine pulley, it is a clutch lining material, and an alloy wheel that moves across it, driving. Usually the clutch lining wears out.
if it is just the driven wheel is seized on the shaft you will need to buff the rust off, use some spray (lanolin, wd 40 etc.) and get it moving, anything further pictures will help a lot