I just wanted to share a little experience that may be of use to others at some point. Earlier today I received a watch back through the post that had been away for several months. It's a 1966 Omega Seamaster Cosmic Cal 601 that was always very accurate, running at +2 seconds per day.

After winding up the watch it became clear within a short time that the second hand was visibly fast and over the next two hours it gained a shocking 20 minutes. I suspected it may have become magnetised but fortunately I received a tip from Private_Doberman here on the forum who pointed me to a thread on Watch U Seek about Seiko watches running very fast.

The first post in that thread discusses tapping the side of a watch on a table to fix a problem where the hairspring is vulnerable when unwound but better controlled when the mainspring is wound. He suggests giving the watch a hard tap on the side opposite the crown but I tried an alternative solution mentioned further on by turning the watch upside down at 45 degrees to my body and tapping the back of the case half a dozen times with two fingers. Quite amazingly the second hand visibly slowed and over the last two hours has kept perfect time to the second.

 

Very interesting tidbit! Always fun to get these little reminders that we have fallible mechanical instruments on our wrists - very well-made, but not immune to the forces of friction and gravity

 

Can't wait to hear what @Archer has to say about this!

 

It's called the Two Finger Regulation not to be confused with the One Finger Response.

 

At times a watch will receive a shock at causes the balance spring to temporarily move from it's normal position, and if you are unlucky enough the spring can get hung up on the stud carrier. Some watches are known to have this problem because the geometry makes it quite easy to have happen, and some Seikos are well known for this happening pretty regularly. The last instance I saw of it was on a ladies Rolex with a 2135 I had serviced:



The watch owner swears the watch was never bumped hard, at least that she could remember. As you can see at the red arrow, the balance spring has been caught on the stud carrier. This will cause a fast rate...some might even call it "crazy fast!"

Here is another 2135 that has the spring in it's normal position, and you can see that the coils are nice and flat, level, and they are also concentric:



So although I don't know that the 600 series from Omega is prone to this (I have not seen this happen on that movement), it could be that this was the cause of the "crazy fast" rate the OP had.

The solution given for a Seiko on forums is typically to smack the watch in the palm of your hand to dislodge the caught spring. If you want to smack your watch around be my guest, but that would not be what I would prefer to see people doing. As in the Rolex example above, I first diagnosed the cause of the fast rate by opening up the case and observing the movement, and once I saw the problem I dislodged the spring with tweezers and checked that it had returned to it's nice flat, even, and concentric state. Often the job is not done when you have simply dislodged the spring, as it will need adjusting again after being distorted.

A fast rate can be caused by many things, so assuming it's this and smacking it around would not be my advice.

Cheers, Al

 

Just to be clear I definitely didn't smack the watch around. It was merely a few taps with two fingers on the back of the case. I would never hit the watch against a hard surface or use any kind of real force. I've just checked and it's currently running at +7 seconds per day.

 

I know this is an old thread but I want to thank the OP .
I had a very similar experience with my recently serviced 1964 seamaster 600.
It was keeping accurate time after servicing but I noticed yesterday ( about a month after servicing ) that it was running extremely fast .
It gained approx. 10 minutes per hour .
I thought maybe it had been magnetized .
I checked that with a phone app and it showed no magnetism.
Then I came across this post , I tried the " two finger fix ", and it worked !
The watch instantly slowed and has been keeping accurate time for the last 24 hours.
I may still take it back to have it looked at just incase .

Again , thank you Sgt_Bilko and Archer for the technical explanation.

 

I'm glad I found this thread on Google. My modern Ploprof was running fast, about 5 seconds a minute. Crazy fast.

I bought a demagnetizer and that did nothing. I was just about to take the watch to Omega. I had it serviced by them 5 years ago. And 18 months ago they replaced all the seals, as there was an issue setting the time. So I really didn't want to spend $550 to get it serviced.

I tapped it a few times, and sure enough, it's keeping great time now.