so i re-checked all the gears and the piston and they are OK, as for the motor position I tried pushing it all the way up and holding it by hand and it still doesn't fire... I'm not an expert so right now i'm lost
what confuses me the most is that the gearbox works if it is outside of the rifle...
PS for the noises at first it sounded like the half-thooted gear was grinding on the piston but there's no sign of that and after i took it apart and put it back in it sounded like the motor was spinning without touching the miter gear but again no sign of broken teeth...