Well after finally removing the stereo from the car, I decided that I was not going to try to take the unit apart in order to find out why the CD player is jammed with the last owners CDs in it.
It will be interesting to see whether the guy I've given it too can sort it. In this part of the world there tends to be a 'call back tommorow / come back tommorow' attitude to everything. I hope my unit doesn't go down this route.
Anyway just in case it gets completely trashed I'll be on the lookout for one in fully working order. Trouble is postage costs would be a fortune.