I have taken the amp to tech and he told me that it shouldn't be a problem to fix it.
The yellow wire was just cut and taped, and although on the picture here looks like it's going back inside the transformer it just felt that way when we opened chassis. As tech explained me, someone just converted with those red wires transformer to work on 220V, and if transformer works good, that wouldn't be a problem at all. They have also soldered those 2 diodes like you noticed and made rectification solid state, and I asked tech to make me a switch, cause I already have one hole in the chassis where original fuse holder was, to switch between solid state rectification, tube rectification and both at the same time.
I will also try KT-90 instead of KT-88, because they're domestic EI Nis tubes here in Serbia and I can find them cheap, I've heard that it's a good quality tube.
I will post more pics when I bring this beast to life, and maybe some sound samples too.