The VW windshield wiper motor and assembly is a pretty small, powerful and trouble free affair. If you're having problems it's most likely in the lubrication, brushes, or alignment. Remove the cir-clips that hold the arms to the motor, pull the arms and test the motor alone. Lubricate and test again. It ought to run strong and sweet at both speeds. If it does, bust down the assembly right down to the rotating pivots, clean thoroughly in a bucket of paint thinner, lubricate with white lithium and reassemble. If it DOESN'T run true, open it up, clean the armature and contacts, change out the brushes, and reassemble, THEN bust the rest of the assembly down to the pivots, and refurbish for good measure, anyway