Regarding y-day-s events something also scratched my film. I guess both Zorki and cassette need some serious cleaning.

Industar 61 - there's hardly anything to go wrong with this lens. I've unscrewed the rear part, cleaned all I could and screwed it back together tightly. The rear element (group) is mounted in a separate barrel, there's no chance of it being mounted backwards or misaligned heavily. If it's bad, I can't do much about it. The barrel is aluminum, but the screws are steel, and it all corroded beyond the point where I could unscrew it. It's not missfocused, but something is misaligned indeed. I'll do my best once more, shoot three frames and if it'll be bad - c'est la vie.

I'm not sure if problems with there cameras are limited to poor manfacture, looks like former users were also poor, not servicing them.