Good for a general idea but if it’s slowed perceptibley, then set it against a computer and wear it for a couple of days. Then make a very small adjustment (literally if you see it move you’ve gone too far, then repeat daily until it’s close.
Exactly what I did with my Seiko SPORK, it was gaining lots, at least a minute a month, so I asked a mate who’s a goldsmith and does a bit of work on watches, but after he had a couple of goes it was just as far out, so I bought the appropriate case back opening tools from Maplin and had a couple of goes myself, the second attempt went far too far, so I nudged it back very slightly, closed it up and kept an eye on it, and it gained around thirty seconds over six months, which I thought was acceptable.
It’s now gone out again, just over a minute slow since the clocks went forward, but it’s a few years old now, so I figure a service might be in order, so when I pick up my Yema from the people who’ve been fixing and servicing it I’ll ask them to look over my Seiko.
People I’m using are Deacon & Son, in Marlborough, they also have branches in Swindon and Royal Wootton Bassett, they have actual watch makers, two of whom were in Switzerland undergoing training when I phoned them a week or so ago, so I think they might have a bit of a clue about fixing mechanical watches.
