What is causing my 21j movement to lose time?

[Prsist]

My Rolex 21j movement loses significant time when left on my watch winder but keeps perfect time when on my wrist. The watch is maybe 1.5 yrs old. Any ideas?

[Jkay]

Just a shot in the dark here, and maybe a stupid suggestion, but you know that a21j only winds in 1 direction, right? Is your watch winder spinning the correct way?

[upland]

Body temperature= rotor lube temperature ====>more rotations> more power reserve > more accurate i am a genius

Or, some soul connection.

[plaifender]

could be a host of things. it's a 21j.. maybe you'd consider getting a new 21j movement for the watch. I'd open it up and see if it looks dry or not.

[TeeJay]

If it's keeping perfect time on your wrist, that's all that matters

[Prsist]

It's strange, up until a week ago she was fine on the winder.

I didn't know 21j's wound one way.

How do I tell if the movement is dry?

[crystalcranium]

It's a shame, the solution is so close yet so far. How does the watch do sitting dial up with no movement? Anyway, I would agree with TJ who suggests if its fine on the wrist why complain but I don't think it bodes well for the mechanical reliability of your watch in the long term. The shame is these Chinese movement can be had commercially for less than $15 USD. If you can pull the hands and remount the datewheel overlay onto the new movement, you can swap out movements easy as that. If you can't having someone do it will cost a bit, sometimes more than the watch is worth. Unfortunately, the A21j movement doesnt make sense to repair since fixing one far outstrips the cost of replacing one.

[TeeJay]

I definitely think this needs further investigation, before going to outright concern I would suggest the following bench test:

Synchronize the watch to your PC clock, and wear it solidly for 24 hours (don't remove it to sleep) and then check it's accuracy at the end of the 24 hours. Synchronize the watch, and repeat the 24 hours of wear and observation, just to ensure that the +/- is consistent. Then, fully wind and synchronize the watch again, but rest the watch against a book or something on your desk, so the watch face is at a 45 degree angle (with 12 to the top, as per normal viewing). From my own timing/regulation experiments, I have found that this angle best negates a movements' tendency to gain or lose time depending on which direction the watch is resting, so you can again, monitor the watch for 24 hours, before again comparing the +/- to the pc clock (it should be the same difference as if you are wearing the watch) Then, leaving the watch in that position fully wound, see how long the watch runs before the power reserve gives out. I am assuming of course, that the watch does not stop at all while you are wearing it. I found that the movement of my PAM 127 started stopping when it was in need of servicing, but of course, that was a manual, rather than auto-winding movement Best of luck with the experiments

PS Once the watch stops on the desk, fully wind it again and replace it in the same position, and time to see if the movement stops after the same lengh of time. Again, you are testing for consistency of performance, rather than 'fault diagnosis' at this time