I really dont have an answer for ya. But this may help.
If your talking about the switch for high to low on temp control mine is pretty loose to. turns easy. The key needs to be turn to warmer position. You basically have 4 options. The key switch, low to high adjustment, the hand warmer, or bad wire. If it was me I would take a meter and start checking for voltage starting at the wires going to the handle bars and work my way back. until I did not have any voltage. If you have voltage at the grip more then likely the hand warmer itself is bad. I think these put out a 12v a/c