sks safety question

I've got an SKS with a safety that just flops back and forth.

I took the trigger assembly out, and reinstalled it, same result, floppy safety.

I haven't seen this particular rifle before, someone brought it to me to fix.

I can't tell if something is missing, or I'm putting it together wrong.

Thought someone here had seen this before.

Thanks

is it a russian SKS? early or late russian?

It's a Chinese Norinco.
It has a 20 round, nondetachable, Chinese magazine, which may be causing part of the problem.

just a note, the safety only locks the trigger not the hammer.