Originally Posted by Jon Williams

So, let me contribute what we at our track (Al Sodano discovered this) believe may be *one* of the reasons a few people are shredding spur gears:

When running a 92T spur with certain pinions the motor can press into the top deck when it flexes causing the pinion to temporarily move away from the spur.

Anyone having this issue should give a 96T spur a try and make sure there is some clearance between the motor and the top deck. (When running 17.5-13.5 I only run a 96T spur because I like the placement of the motor in the chassis.)

If you prefer to run a 92T spur you could try dremeling some of the material away from top deck near the motor.