An update. I spoke with the repairer today on the off-chance that my camera had arrived (I sent it by registered post which was supposed to take 3 to 4 days). Not only has it arrived, but he has just about finished servicing it. He said there is a hub which holds a spring which was pretty much clogged up from lack of service. It will be on its way back to me tomorrow. Thanks again to Steve for his very quick help and recommendation of a great service man.