Beng, I bet your 'issues' with the firing pin and the spring were really the 'transfer bar' all along. I know, a lot of help that is......now......
They look like a simple action, and are, but things have to work in the right relationship and 'timing' to function correctly, just like any other mechanism. I fear that some of the 'assemblers' are not craftsmen, and maybe there has been a turn-over rate among those people that has not helped at all; it takes time to make someone good at it.
I really hope you get a well functioning rifle back, they can be very satisfying, as many here have confirmed.