zimzalahbim,

Tough for me to say, but pretty much everyone I know that runs a 777 uses that box.

This may help, the front 90 degree plastic pieces on mine are turned around backwards, so the front chassis does not "lock" into them, it simply rests up against them. Then to start it I push the rear down to get the starter box motor running, I then push the front down to engage the flywheel.