Well I'm no expert but, beyond all of the other vintage watch criteria, I looked for one in very good condition with a movement picture that looked good. When looking at movement also made sure there wasn't evidence of prior battery leakage. I then asked about the date change since these plastic date wheels can be an issue. all was well so I went for it. Oh, forgot to mention the price was right too!
😉
Make sure there is no corrosion around battery, or anywhere else for that matter. These aren't very expensive so waiting for a nice one is advisable...patience is your friend here.
😀 I was really looking for a steel one but this one was so nice I couldn't resist.
So far, so good!😉
P.S. I'm sure the more knowledgeable on the Tuning fork movements will chime in as well.