from what I understand yah, those 2 gears should be changed, but the question I'm sure we are both thinking is what gearing? Your motor may have died because of the gearing being to low and making the motor work too hard. I'm trying to prevent that before I even open the package. I know what it comes with stock, and this is taken directly from the owners manual:

Diff. Main gear - 64T
Motor gear - 17T

I was suggested by pede_kid to use a 12t pinion and larger spur gear. I'll try that. If anything I have the stock motor to put back in if it is unsuccessful.