Parts that have broken for me are firing pins and disconnects.
The design of the TT-33, with its positive firing pin, puts shear force on the FP as the gun unlocks - the "pin wipe" you see across the primers that can run right into the side of the primer pocket.
Buying used parts taken from unserviceable pistols to replace high stress parts isn't a game I will play any longer.
I sold my Tokarevs and won't look back