LipoXrayEvo2

Hi, I have a MGT with the XTM 457 motor (which is prob why this is happening)
Anyway, I keep snapping my rear drive-shaft CVD pin right on the transmission output cup.
If I loosen up my slipper it "slips" and melts my spur gear.(should I invest in the steel one?)
If I tighten it back up it snaps the pin.

So basically my question is, is there an upgrade for this that I haven't found?
And, how tight should I make my slipper?

Thanks everyone.