John and Bob,
Thanks for the suggestions. John , you were correct. It was always stopping when the one repaired tooth on the second to the last gear in the time train engaged the last pinion. Ratio is 4:1 so it happened once every 4 turns of the escapement wheel. The tooth was a beautiful old repair, they even grooved the repair to match the rest of the wheel, but on magnified examination the repaired tooth was slightly thicker than all the others. I carefully sanded just a bit off and it has been running for 6 hours. I think the other cleaning and bushing helped in that it make the stopping consistent. Many thanks. This is a great place to get help.