The first thing to do when a Gérald Genta mechanical watch starts running slower is to check the winding mechanism. The winding mechanism is an important part of the mechanical watch and is responsible for providing power to the movement so that it can run properly. If the winding mechanism has become worn or is not working properly, then it will cause the watch to run slower.

In this case, it would be advisable to take the watch to a professional watchmaker who can check the winding mechanism and make any necessary repairs or adjustments. The watchmaker may need to open up the watch and inspect the winding mechanism in order to determine the cause of the problem.

Once the problem has been identified and repaired, then it is important to perform regular maintenance on the watch to ensure that it keeps its accuracy. This includes cleaning and oiling the movement and checking the watch’s timing. It is also important to keep the watch away from moisture and dust as these can cause further problems.

If the watch is still running slow after all of these steps are taken, then it might be time to consider replacing the watch. While Gérald Genta mechanical watches can be expensive, they are well worth the investment as they will last a lifetime and provide accurate timekeeping.