If the clock has done quite a few years service, there may be another factor contributing to the problem.
As the shafts of the wheels turn in their holes in the frame, they gradually wear the holes into an oval shape, and the gears don't mesh properly, increasing the load on the gear train.
A clockmaker would fit inserts to repair the oval holes, and it could run for another fifty years or so.
The overwinding would be remedied during the dismantling for this procedure.
Munro, May 2011