[MrForbes]

The key and clip were installed just as shown in the picture in the Toughbox User's Guide, shown here.

This is probably a rare problem, but it is something to keep in mind if either you have the transmissions apart to work on something else (it's a relatively quick and easy mod to shorten the key and install the washers) or if you encounter weird driving behavior or noise. With a single CIM per side, you'll have the robot driving in circles, with dual CIMS you'll get one hot motor and one cold motor and drifting or erratic driving.