I was thinking of selling my Zorki 4K on fleeBay (I didn't want to, but am getting 'grief' about the number of cameras I own )

I decided to keep the Zorki when I realised they sell for such very low prices. Maybe it is because of where I am... (UK), but I'd check your local ebbeeGumay and other outlets, paying myself even the minimum working wage I wouldn't spend more than an hour on one before chucking it in the bin and buying another becomes the only sensible option - unless of course you really *need* to fix it.