How do I get the gearbox out of the casing here?

[paradoxum]

I'm trying to get to the trigger to solder a NanoAAB mosfet sensor wire to it and replace the main spring, It's a snow wolf m14a pulse rifle which is basically a thompson with a shell, I can't figure out how to get the gearbox out of this plastic housing bit though. I've tried everything but it won't budge. any ideas?

 

[BigStew]

the safety and fire select need to be removed they should be held on with grub screws

 

[paradoxum]

Got it thanks. 

Took the gearbox apart and gears and washers and springs allover the place. Bagged it all up and just going to call a shop tomorrow about sending it to them to sort out. Or anyone on here do paid work? I need the mosfet sensor wires soldered up and just the gearbox put back together and everything.