I'm not sure if this is the correct place to post this. On a piece of equipment, I purchased new, the clock ran slow. The second clock that was installed ran slow---it lost approximately 4.1 minutes in one month. Below is what I sent the Service Manager who I understand thinks it is possible to test the newly installed clock immediately after installing it with a cell phone (the NH Rep thinks it's possible also, I understand. (I did not measure the time initially with the precision indicated below but just included all the digits displayed by the Windows computer calculator and actually, if you round up, the clock loses approximately 27.8 ms per hour.) Even if a person had a super precise stopwatch, there would be a time lag between seeing the digit or digits change on the clock being timed and pushing the stopwatch button. So I suggest timing a newly installed clock for a period of preferably two weeks approximately to get an accurate assessment of the clock accuracy.
"You mentioned something about possibly checking the accuracy of the clock with a stopwatch while up here. It’s not possible to check the accuracy of the clock right away after installing the instrument panel, like I mentioned since the current clock loses a small but cumulative amount and it is impossible to accurately time such a small interval of time with a stopwatch. In my email dated February 7, 2018, I write, “Difference between clock and watch in three weeks was 14 seconds or 14 / 21 = 0.6666666666666667 loss in seconds per day.” So, in one hour, it loses 0.6666666666666667 / 24 = 0.0277777777777778 seconds. That is 27.7 milliseconds in an hour. I don’t know how you could time it so accurately, since just pushing the stopwatch button has some variability and you would have to wait one hour at least and if you were off just a few thousandths of a second, that would greatly affect the accuracy of your results."
What are your comments?