Went by my usual thrift store today but was closed. So I was just driving around and seen a yard sale and decided to stop. Picked up this 1977 Bulova Accutron with a 218 movement. Cleaned it up a little and put a new battery in. It's working, but its running considerably slow. In fact, very slow. 20 mins slow in the past 30 mins. Any suggestions what the problem might be? Thanks.