If your clock runs but isn't keeping time, running slow, make sure that after you set it that the knob/cable is fully disengaged because the spring that pushes the knob back out may not fully disengage the gear inside the clock.
I found that was making my clock run slow. I just pulled it back and twisted it left and right to be sure it was all the way back out of the setting position. It has kept time ever since. It is an OER repro. My original is in a box. It did not work at all...
It does not stop it but can have just enough contact to cause slight friction and slow it down. If it runs fast, I don't have any suggestions.