The theoretical solution is plain and simple: lubricate it. In practice, however, this means removing and disassembling the motor (as described in the answer to the previous question)—not something you would want to do every six months or so, wouldn't you? But if you do it once, you can modify it so that you can lubricate it later as often as you feel necessary without going through the hassle of removing it any more.
Indeed, the word modification is an overstatement. All it takes is drilling a small hole in the casing. The motor is located in the left side of the housing, secured by two bolts (to remove it, its two connectors must be removed as well). There are several radial reinforcing fins of the plastic half-case facing the engine between the center part housing the motor and the perimeter. The upper vertical one is about 1 cm wide and is situated exactly above the motor mechanism. Drilling a small hole in the lower third of this fin will be more than enough to allow the motor below to be lubricated whenever necessary. After that, it can be covered with adhesive tape to prevent the ingress of dirt.