Re: Seamaster 300m running fast.- May need cleaning, oiling,
It is also possible that the balance wheel is gummed up a bit, particularly if your watch sat in a display at the jewelery store for a year or so before it was sold to you. The lubricating oils can settle in areas if the watch remains stationary too long, especially under hot, bright showcase lights, resulting in the balance wheel not making its full swing. Well, at least that's what my local watchmaker told me. However, the above response could be true too so his advise is sound. Take it to your watchmaker and let him make a determination.