Zenit 12XPS

Ciao guys ! (sorry for my english)

I bought Photosnaiper FS-12 and his Zenit 12XPS in perfect condition (or nearly...).
It has only one defect; the film speed selection ring is loose and lifted.
This allowed the leak of elements I do not know (spring, ball, spindle ?????).
On the top cover is present, under the ring in a regular position, metal part with some small holes
where they probably have to be positioned the elements that have been lost.

What are the missing components? How do I reposition them?

thanks a lot. Luigi

It could be a springloaded ball or a embossed blade spring.
But even if someone knowledgable chimes in, if it is more than a steel ball and a tiny helical spring that is missing, you would need propriatory spare parts. Thus a donor Zenit body of similar design.