All Power Probe 3 circuit testers have a field replaceable rocker switch. The original design features a soldered in switch while the new design is a press in switch. Please verify if your Probe III is the “old style” or “new style”. The “new style” Power Probe III has two slots, one on each side of the rocker switch. If these slots are not visible on your Power Probe III you have an older style Power Probe and the unit must be opened to replace the switch. We have included directions for replacing the switch in both the old style and the new style.  Please verify which style you have before proceeding with the switch replacement.