Omega Seamaster gaining about 10 minutes per hour

My 1950s self-winding women's Bulova wrist watch suddenly started gaining 10 minutes per hour.

Hi, If under warrantee certainly return it for service. I can categorically tell you it's not a broken mainspring. If it were it would not run period. It's probably not rated correctly however if purchased new this is not likely. If you have had similar problems with other mechanical watches you may be better off with a quartz watch. Problem may have occurred if the watch has been subjected to a strong magnetic field.

Hi honestfunguy. Take it back! Omega watches are usually guaranteed for 2 years or even 3 years (Co-axial escapement), so you should not have a problem getting it repaired under warrantee. No way should it be be gaining (or losing) 10 minutes per day, let alone 10 minutes per hour. Could be any number of things, from a broken mainspring to problems with the timing regulator, but they are very complex watches and should not be looked at by anyone apart from Omega whilst in warrantee, otherwise you'll probably void the warrantee. Hope this helps; Eagle58