The one on the right is just a common chime. It's cheaper to just replace it than to try to repair. To repair, the plunger could be stuck or the coil could be bad.
checked for voltage I assume. If you have voltage at the bell and it does not work about the only thing that you can do is make sure the plunger is free to move inside the solenoid and look around for dirty connections and loose wires.
Comment