E12 displayed; unit may start but stops when switching modes or changing brush speed.

Safety first: Unplug the appliance before removing the handle or control housing.

• Check selector knob: Ensure the mode selector knob is not cracked or spinning freely on the shaft. Replace the knob if it does not engage the switch properly.
• Cycle the selector: Rotate the selector through all positions several times with the unit unplugged to clean minor oxidation on contacts.
• Inspect wiring: Access the selector switch and verify that all wires are firmly connected. Reseat any loose connectors.
• Test switch contacts: Use a multimeter to check continuity between the switch terminals in each position. If the expected contacts do not close, replace the mode selector switch.

Do not force the selector; excessive torque can break the internal shaft or PCB.