I designed a 3D printable LEGO-compatible enclosure for an inexpensive brushed DC motor. The intended use is outdoor holiday decoration, so I fully enclosed the motor to weatherproof it. LEGO Technic motors are fully enclosed in plastic as well. But I recently learned that enclosing a brushed motor is a bad idea since the ablated brush material will eventually short the motor. This is why brushless fans are used around electronics.
Is my understanding correct? Should I not enclose such a motor? (Perhaps the LEGO Technic motors are brushless.)