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So I am a bit of a perfectionist - and I noticed that my GMT Master II each week gains about 12 seconds (wearing about 2 days a week and otherwise in the winder)

I know this is in spec but bought it off to the rolex centre just to have a look see - and they tested it and they were convinced that the watch was as good as it was going to get and if I really wanted I could do the full timing check (which would take a week) but advised against it)

The person gave me a slip from the machine as attached... any person in the know that can help interpret all the numbers?
First off, it is rare to find an automatic watch that performs as well as your watch. You should be very well pleased with the accuracy and precision your watch demonstrates. Further, if you asked for your watch to be regulated/adjusted to achieve better performance, it would most probably be worse after the attempt - best to leave it alone.

Now, here is what the numbers in your report mean:

The "Results and Statistics" side show the position the watch was tested in, the time gain/loss in seconds/day, the beat amplitude and the beat error. The positions tested were crown pointing down, crown pointing left, crown pointing up, dial facing up and dial facing down. The beat amplitude numbers simply show that the movement "swings" an adequate amount and can be an indicator of unusual wear or friction - your numbers are fine and show no problems. The beat error shows the difference in milliseconds between the "tick" and the "tock" of the movement - 0.0 is perfect (no difference), but small differences are usual as the watch position changes and your indicated errors are perfectly normal.

Your results in particular were as follows:

When Crown is pointing Down Gains 6 seconds/day Beat Amplitude is 281 Degrees with no error
When Crown is pointing Left Gains 1 second/day Beat Amplitude is 271 Degrees with no error
When Crown is pointing Up Loses 4 seconds/day Beat Amplitude is 267 Degrees with an error of 0.3ms
When Dial is facing Up No Gain or Loss Beat Amplitude is 289 Degrees with no error
When Dial is facing Down No Gain or Loss Beat Amplitude is 296 Degrees with an error of 0.2ms

On the right hand side of the report are the Range (difference from minimum to maximum) and Average values based on the measurements shown on the left. To wit:

Seconds/day Range is 9.9 seconds/day Beat Amplitude Range is 29 Degrees Beat Error Range is 0.3ms
Seconds/day Average is a Gain of 0.5 Seconds/day Beat Amplitude Average is 281 Degrees and Beat Error Average is 0.1ms

In the upper right hand corner of the report it shows that your movement beats at 28,800 vibrations per hour, it was tested with a lift angle of 52 degrees and the measurement period for each position was 20 seconds.

So, what does all this mean?

1. Your watch is performing very well - you should be well pleased.
2. On average, your watch will gain about a half second per day, but this will vary up or down based on your wear pattern and/or the position that your watch rests in while on the winder.
3. If you want your watch to gradually lose time to compensate for the fact that you are observing that it gains time, you should rest the watch in the Crown Up position.

I'm no professional, so all of the above is subject to correction/modification by those far wiser than I on this forum, but it should be substantially correct.

Any further questions?

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