A bit of a revival, but I got my Speedy back from service about the time this thread was being posted. I initially tested its accuracy, and then noticed a few weeks later that it had seemed to "settle in" a bit, so I did a follow-up timing test this week, and was quite impressed by the results. All timing runs are done using the WatchTracker app for iOS.
Here is the first run, begun immediately after Fedex dropped off my Speedmaster on 8 August:
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Despite some obvious irregularities, the overall rate was excellent at about +1s per day. Considering this watch was +8s/day prior to being dropped and needing repairs, I was very happy to see this result.
After running my Speedmaster for a few weeks, I noticed it had some irregularities, especially right after being wound. It would gain 5-7 seconds over a period of a few hours following a full wind, and then return to an accurate rate. I thought this was strange, so I checked the watch for magnetism using an app called Lepsi, and sure enough, the Speedmaster appeared to have been somehow magnetized! I have no idea how that happened, but I ran it over a demagnetizer, and hoped for the best. After several more weeks of running and not noticing this problem anymore, this is the accuracy I am seeing (17-27 October):
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Note that while the rate has increased slightly, the precision is much better. I have no idea of all the factors that might contribute to this, but I found it interesting. It's worth noting for this test that I consistently give the watch a full wind every morning between 0600 and 0700, which is what I normally do with the Speedmaster. I wore it occasionally during this test, but not every day. When not being worn, it was stored dial up in a watch box on my dresser.
Suffice it to say that I am quite happy with the accuracy and precision of my Speedmaster following service! The mystery magnetism has not been solved, but as long as the watch continues to run in this fashion, I am very happy.
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