Need some help here guys. I am not a an advanced student of Horology but I do most of my own general repairs, Recently I am servicing an 0 sz Waltham Model 1907 (7 jwl). Nothing new as I have done several of these before. After completing the watch I had it sitting on the bench for a few days to watch it. After a few days I noticed it started to lose time (30 mins per day), then it started to run for shorter periods. Upon checking I found something was slipping when I was about a third or half way through winding. I have checked the spring, barrel and arbor, clutch wheel. I also checked 2nd wheel for slippage. I have replaced all those parts from other parts watches but I cannot determine what is slipping. I am guessing it is something right in front of me but I am getting no where, Anyone with some ideas-would appreciate help.

John, those have hole end mainsprings. Check to see if the mainspring is slipping.

Thanks Brian. I think I have eliminated that. I replaced both barrel and spring on 3 different occasions with no help. Each time the hole end is always attached to the hook when I remove the barrel. Seems very unlikely it would happen with three different barrel-spring combinations. It does feel like the spring does slip and that was my first attempt at a fix but I been chasing every way since then.

John those barrels are tricky...The spring has to have the right bend on the end to grab the hook..If they don't have the right bend they will slip when the get a certain amount of pressure and then grab the barrel again when the pressure is released and that is why it always looks like it is hooked when you take it apart.. When I put them in now I always look at them from the outside of the barrel to make sure it has a good seat..I always try to make sure it is at least half way down on the barrel hook..I know you have tried several springs but it might be worth looking at again to make sure it has a good grip on the barrel..

Hi Gary: Thank you for your suggestion. I will check it out again and try to determine if that is what is happening, John

John did you ever find the problem?? Just curious..Gary

Hi Gary. Thank you for your inquiry. I think you and Brian had it pegged but I had to take a working one apart to check how much bend was in the spring. I think I was trying to put too much bend in it PLUS I found the barrels I were using all seemed to have a shallow hook (worn maybe) so I also found a barrel with a longer hook and just yesterday I got it running. I have serviced and repaired maybe 20-30 of these watches and this is the first time I have had this situation. Thanks to you and Brian I think the problem is solved. John

John good to hear you got the watch going..Sometimes those barrels can be a little tricky.. :-)

John,
Another thing you can try when installing a new hole end mainspring is, file a knife edge on the inside of the hole in the m/s. This helps the m/s grab the hook in the barrel, better.

Hi Brian. Thanks for the note. Actually I had done that also. I am thinking it was a combination of too much curve in the hook end as well as using barrels with a small or worn hook. Either way it appears to be fine now. Not sure what I would have done next as I was sure I had ruled out the slipped MS. Again, thanks for the help