About 15 years ago I bought a Hamilton Khaki Automatic with the workhorse ETA 2824-2 movement -- I assume it has the standard grade movement.
For the first decade it ran flawlessly, serviced twice, and kept a remarkable average accuracy of -2 seconds per day (I kept a spreadsheet over several years and compared the time to the NIST time clock).
The watch then went into storage, kept in a closet in a sealed ziploc bag. Recently I decided to wear it again and had it serviced (cleaned and regulated.) Unfortunately, the watch now has an average accuracy of -10 sec/day (which I've been told is still acceptable but is hard for me to accept!), and even when I brought it back to the "watchmaker" to speed up (twice), it doesn't do any better than that.
I don't know what happened, but for reasons I won't get into, I suspect the watchmaker I used is not as experienced as he claimed to be (e.g., he said my watch used an ETA 2892, which shows he does not really know his ETA movements that well so how would he know how to properly regulate the movement?) I wonder if that watchmaker did something he shouldn't have.
So what went wrong, if anything? Was I really lucky the first decade and now my watch is "normal"?
And does anyone here have a recommendation for an excellent ETA-experienced watchmaker in the Atlanta, Georgia area (either professional or part-time amateur enthusiast) to reservice and regulate the watch? I'm hoping to improve the accuracy if possible since the watch had excellent accuracy before -- why can't it again?