Hi and welcome to the forums. Some pictures would be helpful, but from the description, this sounds like the same trouble Gilbert clocks have in that, the pinion that is on the minute arbor tends to crack. I made one by hand, and then Timesavers started selling them for $13 USD and change. I am not sure if this is similar to what you need or not but a picture is worth a thousand words. If you would be so kind as to post some, we can figure this out.
Again welcome to the forums!
Jim B.