Matey who bought the Canon camera still won't tell me what's wrong - I've asked for information and got nowhere. He says a repairer has told him it can't be fixed but he hasn't given me any proof of that. Since the period for the return ends tomorrow I have been worrying about this - so I called eBay to check, and they've told me that in view of the time elapsed since he received it I don't have to accept the return!
So tomorrow, if he isn't a LOT more forthcoming, I will tell him that I'm not prepared to accept a return, but offer my help in solving whatever the problem is if he is prepared to give me more information. I suspect that it will be the last I hear of it, but we shall see.