Not sure why no one's responded but here's my take: I guess you mean clocks that are plugged into the wall? I think most people throw away quartz movements and replace them. AND I'm far from an expert on this subject. If I wanted to learn electric clocks I'd just start buying them cheap and repairing them or inviting the business and learn. All here would be of help. Basically, many electric clocks are simply a common clock movement with an electric motor instead of a weight or spring. Typically, the motors are synchronous type. That is they run because of the 60 cycle alternations of electric current in our home. Simply, there is a field winding and a rotor and no physical contact between them ( hopefully ) If the field has continuity, that is it's not "OPEN" somewhere - it emits sixty pulses per second to the rotor and the rotor turns. Typical problems here are several; 1. The field is open. No current flows. 2. clearance is lost between rotor and field and rotor rubs field. and 3. It is very common for the drive gear on the motor to fail and lose it's teeth, then unable to power the clock. In most cases you'll need only a minimal amount of electrical knowledge and perhaps a voltohmmeter and soldering iron ! I wish you well my friend and ask more questions if you have any.