[MrForbes]

"<R61> So that the maximum power level of every ROBOT is the same, motors used on the ROBOT shall not be modified in any way, except as follows:

The mounting brackets and/or output shaft/interface of the motors may be modified to facilitate the physical connection of the motor to the ROBOT and actuated part.

The gearboxes for the Fisher-Price and Globe motors are not considered “integral” and may be separated from the motors.

The electrical input leads on the motors may be trimmed to length as necessary.

The intent is to allow teams to modify mounting tabs and the like, not to gain a weight reduction by potentially compromising the structural integrity of any motor. The integral mechanical and electrical system of the motor is not to be modified. Note that FIRST will not provide replacements for modified parts."

As I read this rule, it lets you play with the gearboxes on those motors that have "separate" gearboxes, but not on those that have integral gearboxes such as the window motors. Although you are allowed to modify the output shaft (which is essentially a gear or a splined shaft on the window motors).

Definitely worth asking on the Q&A, but be very specific that you intend to replace the internal gear, not just the external one as Dave apparently assumed.