check on
www.mechbox.com
Theres a M733 take down which should help u, but be careful because if u have a plastic reciever its easy to snap the tabs
The M733 takedown will show u how to get the gearbox out then u gotta find the Version 2 gearbox take down and that'll show u how to take apart the gearbox and replace the spring.
Its a long process, and it takes A LOT OF patients espectally if its your first time, I just opened my TM M4A1 and by far the hardest thing was putting the gearbox back together... stupid anti reversal latch
Or just find a local gun doctor thats probably your best bet
http://www.mechbox.com/site/m733-disassembly-video.html
http://www.mechbox.com/site/version-...ade-video.html
http://www.mechbox.com/site/m733-resassembly-video.html
Those videos in that order should help u