Read the four cells. Good amplitude with a steady rate error is a regulation. Falling amplitude across the wind is a service. A sudden large rate error with good amplitude is magnetism.
Does my watch need a service or a regulation?
issue ISSUE 01checked 2026-09-16rots yes — these figures moveresponsible Escapement Papers (a named bench, not a person)
What you need A timing machine with the movement's lift angle; a full wind; readings taken at full wind and again after 24 hours.
tape card: the four-cell decision
| Rate | Amplitude | Verdict |
|---|---|---|
| Steady error | 250-310 degrees | Regulate, and demagnetise first |
| Steady error | under 200 degrees | Service: the train or lubrication |
| Large sudden error | 250-310 degrees | Demagnetise, then re-read |
| Erratic | falling across the wind | Service: mainspring or barrel |
Steps
- Take the four readings at full wind, with the lift angle set and written down.
- Demagnetise and take them again. If the rate returns to normal, the job is done and no service was needed.
- Wind down and take a rate and amplitude reading again after 24 hours. A healthy movement loses some amplitude; a tired one loses a lot.
- Compare the amplitude at full wind with the amplitude at 24 hours. A drop of more than about 40 degrees points at the train or the mainspring, not at the regulator.
- Only then decide. If the amplitude is healthy, regulate. If it is not, no amount of regulation will hold.
Why amplitude is the deciding cell
| Cell | What it separates | Decision it drives |
|---|---|---|
| Rate | A regulation problem from everything else | Adjust the regulator |
| Amplitude | A tired movement from a healthy one | Service or regulate |
| Beat error | An adjustment problem from a wear problem | Adjust or replace |
| Lift angle | A measurement from a guess | Void the reading if unknown |
The order of the tests is the point
Demagnetising first costs a minute and can remove the entire complaint. Regulating before demagnetising moves the regulator to compensate for a fault that will vanish, and leaves the watch wrong once it does. Testing the amplitude across the wind separates a tired train from a mis-set regulator, and it is the test that most often changes the answer.
A watch with a steady rate error and a healthy amplitude is a regulation job, and calling it a service is the most common expensive mistake in this subject.
A position to argue with
The bench holds that most watches sent for a full service needed a regulation and a demagnetisation, and that the four-cell card above is enough to tell the difference in a majority of cases. A watchmaker may contest the proportions, and the way to settle it is a series of before-and-after readings with the lift angle stated.
References
- Ref 1Lubrication, Horopedia – Watchmaking Encyclopediasupports the lubrication state that a falling amplitude points to
- Ref 2Lubricants, Horopedia – Watchmaking Encyclopediasupports the lubricant behaviour that a service restores
- Ref 3Mainspring, Horopedia – Watchmaking Encyclopediasupports the mainspring behaviour that shows up as amplitude loss
One link, one document, titled as it titles itself. No home pages, no search results.
Set this page down Set this page down when the amplitude cell has told you which job you have.