Please DO NOT remove the rear end bell. You will most likely damage something inside. The warranty will not be honored if interior damage is found. Screws which are too long will contact the stator coils and cause a fatal short. This is not repairable, so please be careful.
Gearboxes provide a means to obtain significant performance improvement over direct drive.
They allow you to turn a much larger prop at lower current, while operating the motor nearer its peak efficiency rpm. A small vial of special teflon gear lube is available from us. The Max15 Series motors are manufactured with a .1872 dia. Our prop driver is CNC machined to very close tolerances to provide the recommended shaft fit. It is suggested that you apply a drop of 222, or 242 Loctite to each of the setscrews when installing the prop driver on the motor shaft.