Model A speedometer question

[woodrow]

When I got the "new" '31 Model A last week the speedometer didn't register so I've been messing with it to see what is needed. Yesterday I removed the cable and speedometer head and the gear drive that fits on the drive shaft. I see that the speedometer head does work. I made a little gizmo that's the size of the end of the cable that goes into the head, put my power drill on it in rerverse and it registers just fine. This morning I put the power drill on the end of the cable that fits on the gear drive and the other end back into the head, spun the cable in reverse and it works fine. When I removed the gear drive from the drive shaft I noticed the cap that screws the end of the cable to the gear drive was broken, however both ends of the cable were in the head as well as the gear drive but it didn't register when I drove the car. I'm wondering if the teeth on the gear drive were not messed with the gear on the drive shaft---how can I check that? I see there is a thin gasket still in place on the drive shaft where the gear drive fits but I didn't remove it since I didn't want to mess it up. I'm open to suggestions as to what I should do next. Thanks