[Al Skierkiewicz]

I assume you are talking about the locking pawl in the drill transmission. Many teams leave this part in thinking that the braking (locking the output shaft) is a good thing. If your travel speed is fairly high, when you remove drive from the motor and the locking mechanism clicks in, damage to the transmission is almost assured. Remember the locking mechanism was designed to lock the shaft to allow turning screws while in the screwdriver mode of the clutch. With the new motor/transmission we have this year, that may have been addressed differently by the manufacturer.
Brake mode on the speed controller causes both the low side FETs pairs to turn on producing a dead short across the motor. As the motor is being turned by the momentum of the robot, the motor acts like a generator and dumps all of it's current into the dead short of the speed controller. (In practice the load is the resistance of the FETs in "ON" plus the resistance of the wire between the motor and the controller, or roughly .1 to .3 ohms.) In coast mode, all FETs are turned off and the motor has no electrical load.