Servicing an electric knife

The reciprocating motion of an electric knife’s two blades is caused by a special gear that has an off-center cam on each side. As the gear is turned by the motor driven worm gear, the two cams rotate out of alignment with each other, simultaneously pushing and pulling two drive arms that move the knife blades back and forth in a sawing motion.

If the knife does not run, the switch contacts may not be touching when the switch button is depressed. Remove the housing and bend up the end of the upper contact with pliers; if the contacts are dirty, clean them with fine sandpaper. If the knife vibrates or is noisy, run it with and without the blades attached to determine if the problem is that the blades are either worn or bent; replace the blades if necessary.

Replacing the knife’s drive assembly. 

If the motor runs but the blades do not move, remove the housing and unscrew the drive-assembly cover, exposing the gear and the drive arms. Remove the gear by pushing out its retaining pin; install a new gear, greasing it well with petroleum jelly before you reattach the retaining pin.

If the blades fall out of the knife handle, either the drive assembly is cracked or the retaining clip that holds the blades is broken. Replace the entire assembly as a unit by first removing the gear, then lifting out the drive arms. Install a new assembly in the same position as the old.