It is important that you take your wall clock to a shop that has the proper tools to service your clock. Clocks can be victims of poor quality repair by “benevolent” repairmen, who mean well, but do more harm than good to the clock. It is not uncommon to pick out an under-qualified repair shop, or a shop that does not use, and install brand new factory, genuine parts, having the clock perform worse when you get it back.
In order to have your clock running in top shape, it is of much significance that you have it serviced by a shop that has the proper tools to do the job right, and to be dedicated to do the job well.
Wall clocks with pendulums are mechanical clocks and the movement of the pendulum regulates the time.