I recently purchased an Omega Speedmaster Automatic 3511.50 (39mm). I bought it online from a Japanese seller with a good reputation (on watchuseek.com and elsewhere) and decent return policy.
The watch came with the original box, warranty card, and (it appears) the full 7+" bracelet. It's in great condition.
The first two weeks I had the watch, it ran a minute or two a day behind. That's not great, but tolerable. The date also did not change until 4 or 5 am.
Over the last week, however, it has not run well. It sometimes completely stops and needs to be shaken to start up again. Other times, it will run 5 minutes or faster over the course of an hour.
Although winding the watch may restart it when stopped, it does not seem to have any other effect and the inconsistent time keeping continues.
I have contacted the seller and they have agreed to accept a return (they have asked that I pay return shipping).
I don't know enough about watches -- admittedly -- if these time keeping problems are fixable for a reasonable cost while doing a service or if they require significant and costly repair.
My dilemma is this: (1) Should I keep the watch and immediately take it somewhere for service? or (2) Return the watch and look for another one?
If servicing the watch makes the most sense, I'd appreciate recommendations for a watch repairer.
Thank you for your help!