To test each segment of circuit, disconnect bell wires at transformer to deenergize bell circuit. A continuity tester can never be used on an energized circuit. Disconnect transformer wires at bell or chime, and twist them together so they make contact with one another. Go back to transformer and touch probe leads of continuity tester to bare ends of bell wires. If tester lights up or you get a reading on meter dial, circuit has continuity and there are no breaks or loose connections in line. That part of the circuit is all right. If tester does not register, there's a break somewhere. If that segment is fault-free, go on to next segment and check it the same way.