Mad Rat stripped gears?

[trf415]

ok, today i took my mad rat out again, i have run this setup for the past 2 runs:
6.5 brushless (nosram)
nosram 5300 28c lipos
19t pinion gear.

the drive in the rat suddenly stopped in the rat and when i got it inside and opened up the gears/diff thing one of them had crumbled,(see pics)
are there any upgrades/compatible parts to stop this happening again?



Thanks in advance!