8) Pull the case straight off. If you must move it, wiggle in a direction that will force the worm gear against the large drive gear. At least in a VW Beetle motor, it is possible to remove the case at an angle and pull the motor armature out too. This is not a disaster, but is certainly a headache. The BMW motor armature may not come out, but you don't want to find out. There are large stationary magnets inside the case, so it will seem to stick.

9) Lubricate the bearing in the inside end of the case.

10) Reassemble the motor, and plug in the electrical connector for a test.