I've opened it up three times now. Still no sign of the broken tooth. It's not in the clear plastic gear housing as Art suggested. I checked.
I don't want to take off the speedometer needle to take the face plate off as I've read it can break due to it's age (269,000 + miles).
However, I've had a good look inside there as much as possible with the face plate on, and really don't see where a broken tooth could get hung up. I've turned the dials and nothing comes out either.
Plus, it ran continuously for 311 miles without an issue before temporarily stopping again. That doesn't seem to me like it would point to a broken tooth being lodged in there.
Cracked solder locations? Well, if that's the issue, I don't think I'm going to go there. I examined them, and as far as I can see, they look okay, but I don't think I want to mess with trying to reinforce them with more solder. I'm concerned I may screw them up, add too much solder or something that would affect their functionality. I imagine I would have to reinforce all of them as they all look about the same to me.
So as it is now, the odometer will turn over for a while, then stop, then start again and go for a while, and then stop. At one point it ran continuously for 311 miles, as I indicated above. So I don't know what my next step is here.
Any thoughts? Daikhster.