Vacuum shows E10 and runs only at a single speed or not at all when speed is adjusted

Safety first: Remove the battery before opening the housing or touching internal controls.

• 1. Check external knob: Rotate the speed control knob through its full range. If it feels loose, skips, or does not stop at end positions, the mechanical linkage may be broken.
• 2. Inspect potentiometer: Open the housing and locate the speed control potentiometer on the control panel. Check that its shaft is intact and that its connector is firmly attached to the control PCB.
• 3. Look for contamination: Dust or liquid ingress can damage the potentiometer. If there are signs of corrosion or sticky residue, the potentiometer should be replaced.
• 4. Test fixed-speed operation: With the vacuum reassembled, set the control to mid-range and test. If the unit still shows E10 and ignores speed changes, the control PCB may not be reading the potentiometer correctly.
• 5. Replace faulty component: Replace the speed control potentiometer assembly if visibly damaged. If replacement does not resolve E10, the control electronics module will need to be replaced by Festool service.