Tom, IIRC you can rotate the gear to a new position so that it doesn't use any teeth that are missing. I think the gear travel is less than half, maybe a third?
When I purchased the upgrade kit, it included a new switch and a note that the step would operate incorrectly with the old switch. The old switch is a mechanical push switch while the new switch is magnetic. However, I found that on my coach. The step did operate correctly with the existing switch, for which I was grateful (one less thing to have to modify).