I've had an Aiwa F660 cassette deck for many years (more than I'd care to
remember!) and it's just given up on playing cassettes.

So I took off the cover to find that my thoughts of a broken belt was
confirmed. It appears that there's two belts in the back of the drive unit
one from the motor (white) spindle to a pulley and another from this pulley
to another pulley which seems to drive the cassette in play mode. It's the
former belt that's broken and was found to be wrapped around the motor
spindle. Extracting it was an art as it's perished and sticking together
being very fragile in this state.

My question is firstly does anyone know of anywhere I can obtain replacement
belts (might as well do both at same time) and secondly how do I go about
changing them (what parts do I have to dismantle). I'm not a total novice at
repairing hi-fi and have the skills to attempt small jobs especially on old
equipment sure as this.