Must have missed this thread.
I recently received a panic call from a mate I service watches for. He had a friend with an Atmos that was losing time badly. Apparently it had been shipped without the balance being locked. He asked if I could do anything and being a sucker I said yes. As it had probably been dropped at some stage, I suspected that the suspension wire may have been pulled down slightly, thus making the balance turn slower. I wasn't game to try adjusting the length of the wire so I hoped I could allow for it with the regulator.
When it arrived (locked this time) I disassembled the case so I could inspect the movement in detail. I found nothing wrong so after cleaning the case parts I put it all back together on my solid bench and set it running at the correct time. I let it settle for two days and then started timing it the same way
@Wryfox did. I used a stop watch to check balance rotation and also to time the difference between reference time and final tick time. After two weeks of timing and doing an adjustment every two days the clock was still losing time and I'd reached the limit of the retard lever.
Luckily I found a manual where re-setting the regulator is described, so I did that by the method where you set the lever full one way, block the crown nut with a screwdriver and then move the lever the other way and set to mid and start again.
Happy to say after another two or three weeks I had it running on time and it went back to the owner last week.
Couple of pics.
I had to replace the worn out bits of felt on the feet (one had nothing). I don't know what original clocks had so I improvised with hard rubber chair tips.
This was the final timing shot. I set it ever so slightly fast as it's easier to simply lock the balance for a few moments about every three months if needed.
