Use jumper wire with alligator clips

Check the ‘spindle to tool ground loop’. Attach an alligator clip to the cutting tool/router bit from a ground that the spindle is connected to. Try performing tool touch off again, if it works then the spindle is not completing its ground loop from the bit to the rest of the machine.

-You can continue to perform tool touch-offs using this method or you may need to replace the spindle. If you wish to use alligator jumper wire method, be sure to remove jumper wires when finished tool touch-off procedure.