How to Repair a Gardner Bender Continuity Tester

Replace the batteries. Put two new AAA batteries in the tester and check to see whether it is functioning.

Open the continuity tester. First, remove the battery cover, then find the small screws holding the outside housing together. Unscrew them and open take the tester apart.

Check the bulb. The Gardner Bender continuity tester indicates continuity through a small light bulb. With the tester apart, check to see whether the bulb is burned out and replace if necessary.

Inspect all wire connections and re-solder them as necessary. Check for loose connections, especially on the black test lead and alligator clip. Re-solder loose wiring as necessary.

Use another continuity tester to check continuity on the circuit board. Check whether current is entering and exiting the tester. Check where the main red probe connects to the circuit board. Take out the batteries, if still installed, and ground the black-wire alligator plug. Place the continuity tester's red probe on the circuit board connection point. If there is no continuity, inspect the board for any burned-out components, such as diodes or resistors. If so, replace them by soldering new ones to the board.