GMT-IIc erratic

[sarjoo]

Dear folks, I wanted to get your thoughts on what might be the cause of this strange behaviour I am seeing with my GMT Master II of late.

The watch is about 2.5 years old and I have owned it from new, and has never had any other issues. It is worn daily, so there is no question of the power reserve being low. I have noticed it speeding up a lot recently, and by that I mean its not unusual for it to gain 30 seconds in a day, and then no gain at all the next day, and then another erratic jump the day after. There's no apparent fixed gain per day, some days it might not gain anything.

If this was steady gains I'd understand but the fact that it is fairly unpredictable puzzles me. Fresh example, this morning I reset the watch to my phone, to the exact second. Some 7 hours later the watch is now 10 seconds fast. The last reset I had done was about 3 days ago, and over the 3 day period it seemed to have gained a full minute. Some days it might not gain any time as stated earlier.

When I first started noticing this gaining, I took it to a local AD and had them check it over, on a "heart beat" machine and they said it was perfect, one of the most accurate he had ever seen in fact he said. Then I had them demagnetise it for sanity's sake, and if anything that actually made it much worse lol

So, before I go down what seems to be the only remaining course of action (which is to take it to the RSC for them to regulate and/or service it) is there anything you guys can think of that might cause this erratic jumping forward?

I was kinda keen on avoiding a service so soon, only been 2.5 years from new, but seems its heading that way?

Thanks for reading!