Great, many thanks to everyone for their contributions.
Tripod screw - the manual says a max 4.5mm depth. My tripod screw is 4.5mm and so the jury is still out on that one but definitely worth a consideration seeing that it was working just fine until it was attached the tripod.
I've now arranged for this to go a local tech who also feels that a repair is probably achievable
, and then, assuming all goes well, a full service.
But as others have suggested, this sort of issue is just going to get harder as repair guys retire and parts harder to find. There is Sover in the UK, specializes in the Nikon F2, who has just begun running training workshops. A great idea which will hopefully expand the skill base for that particular camera but for rest of us using other marques it could be a struggle.
Jon