Heuer Yacht Timer Ref.653.512 "Century" Not Perfect, partly works
I'm the original owner of this racing timer. I've been racing more than 30 weekends a year since 1961. I've actually used this timer only infrequently, because it hasn't been dependable for perhaps the past 30 years. The main spring winds up, but with continued winding, it then "slips" and the watch isn't wound again. So wind it, and don't over-wind. The watch may start, go fine. But sometimes it doesn't go, or goes and quits somewhere in the countdown.
If you press the Start button, the timer can be started, and keep time fine, but it's not reliable, hence I didn't use it much at all. After winding, repeated clicking on the Start button resets the watch to zero, and then starts again. I never had the watch repaired. I never had the case open. Either it needs a replacement mainspring, or possibly the mainspring just has to be anchored to prevent it from slipping. In any event, performance is very iffy, not ultra-reliable like a Heuer should be...
And, as shown in the photos, the crystal should be replaced.
BUT, this is a very clean Classic. Used very little.
This wristwatch/timer is normally used with a nylon wristwatch strap. These are very inexpensive, and because of Nylon, are available in hundreds of colors, patterns, and options. The original wristwatch/timer was sold with a Nylon wrist strap. I loved it.
Fix it up? Likely double or triple values...
Please contact me with any questions.