Measure before guessing
Note how much time the watch gains over a full day and whether the error is consistent. A repeatable +20 seconds per day and a sudden +10 minutes per day are very different problems.
Magnetism can cause dramatic gains
Mechanical watch components can become magnetized in ordinary life. That should be checked before assuming the movement needs extensive work.
Regulation cannot cure unhealthy amplitude
A rate adjustment may make one position look better while leaving a dirty, worn or low-amplitude movement untreated.
Tell us what changed
A recent drop, strong magnetic exposure or abrupt shift in rate is useful history.