The counter wheel does need to turn and if it does not it will kick out the sensor. I had the same situation on a 9191, but my counter turned freely. In my case it was the central hub between the F and R cogs. It is like a clutch that engages and disenages to allow F and R movement. There is a piece of felt in that clutch assembly that gets worn and/or sticky. It will then bind and fool the sensor into kicking off. I am not sure if the 1000 is similarly designed but it is worth a shot to check it out.