I have a few orb. sanders and recently had the Bosch 3107DVS serviced, after a month I tried to use the sander and the sanding block/pad ( not the sand paper ) kept coming off, the service tech must have changed the wires and it spins in the wrong direction. I am out of state from the service tech. and would prefer to do it myself ? Is their a service bulletin of " How to do it ?"