ZCI 16:1 Reinforced CNC Gears

I had a set of these, on the bevel gear, the teeth that mesh with the spur gear stripped after about a month.
Using a JG Blue motor, 11.1v 1200mah 25c Lipo Battery, decent shimming.
I am an amateur tech, so my tech work is not 100% perfect (far from it), so I may have very well done something wrong. I'll probably give these another chance in the future.