I am having problems with wipers not stopping/parking themselves at the correct position. I took the wipers out to access the blocked drain under the bulkhead. The wiper motor was freed from the mounting assembly to gain access to the drain and bolted back again. The wipers put back and checked for correct operation. They rotate correctly however, no matter how I adjust their mounting position they do not park back to the correct location with either intermittent or full on operation. I have disconnected the battery and motor to see if it reset itself but the problem persists. Any help on this is appeciated,