We have a clock that has a synchronous motor that is intended to run on 50Hz mains. It skips 5 or 10 minutes fast sometimes. I looked up this problem and wasadvised that noise on the power supply could cause the clock to be wrong (but only by a tiny amount). Before I taking the clock apart, I decided to plug my power measuring device in to the power point, and got a reading of 158 volts and 32 Hz. It is supposed to be 237 v and 50 Hz! Since the clock had been plugged into the power point for over 30 years I pushed the plug in and out a few times and got the correct readings. I think there was corrosion in the contacts. However the clock still keeps skipping ahead. The minute hand keeps in step with the hour hand so I don't think the hands are slipping. The clock has earlier had an accident where it fell off the wall 3 metres onto to a concrete floor. The adjustment spindle at the bottom broke off, so I made a new part on the huge lathe out of a 1/4'" bolt turned down to 1/16" on the lathe. I am amazed that it didn't break! I now suspect that a cog in the clockwork is skipping teeth. So that is next weekend''s job, unless anyone has brilliant suggestions. I think I need a lathe 100 times smaller now that I seem to be fixing so many clocks. I have uploaded pictures of all this but they seem to have vanished. I cannot see where to put my user name and password. So this probably won't work!