One of the 1st things I did was check the pivots and and sideshake, and endshake, at the balance, the fork and the escape wheel.
I like the idea of a freefall test though.
Will check it later.
First of all, thank you to the folks who have offered thoughts and ideas.
I tested the lock and draw of the lever as Chris Radek suggested. With one full turn of load on the mainspring, the draw is "smart" in the dial down position, but notably sluggish in the PD position, both at the entry...
Thank you Chris.
I intend to test the lock and draw in the fault position as you describe. I will respond here with results but it will be a few days away. The jewel wear in your photo would indeed be easy to miss and I can see how it would express a problem more dramatically in different...
Thank you Roughbarked. I did not test the draw in the fault position. Great microscopic pic. The line on the machine looks random, no cycling pattern, like when you have a single bad tooth or a not-round wheel.
I have been working on an 8 day travel clock/watch, 16 size, swiss, with a seven jewel lever escapement, non-jewelled train. Fully disassembled, cleaned reassembled, lubricated. No notable wear or issues found.
The timegrapher machine shows a 4 min difference positioanally. Pendant down(normal...