Unscrew the two 5mm M4 phillips screws.

Unscrew the 7mm phillips screw.

Pull off the 25mm gear. (This usually allows the adjacent gear (green arrow, behind the outer bracket) to come off with the motor/ drive assembly; if it doesn't, this gear can be put back on afterwards).

Pull away the main drive motor/gear assembly from the printer to remove.

The 25mm drive gear (yellow arrow) and 30mm gear (orange arrow) can be replaced once the motor assembly is removed.