From Horology magazine, April, 1939
Trouble in the Train
I have a problem that I would like to have answered in your Question Box.
I have had several watches with the same trouble and now have an eight day Swiss traveler's clock. I use a cleaning machine and on this particular job, which was a little more gummed than usual, I brushed and pegged the plates and cleaned the pinions with pegwood also, before cleaning in the machine. After assembling this clock the train is perfectly free and runs completely down, but when I put the fork in and escape it either by pushing the fork back and forth or by putting the balance in and letting it escape normally, it locks up in the train tightly enough to stay locked even with the balance and fork removed. The least touch frees it and it runs completely down again.
I have examined every leaf in every pinion and every tooth in every wheel with an 18X loupe and simply cannot find the trouble. I have encountered this trouble several times before in small watches and by sheer luck got them going, but I do not know why. If you can enlighten me on this problem it will be a very big load off my shoulders and will be greatly appreciated.