Do you still have the old piece of key? You could try a tiny drop of Super Glue to attach the old piece then pull the rest of the key out - don't try to turn it, just pull straight out. Didn't work? All is not lost. Most tractor switches are expensive because they're not real common with that glow plug position. That part burned out on the original key switch on my Mitsubishi. I went to my local NAPA dealer and bought a cheap automotive ignition switch. That let me start and run the tractor but I had no glow plug circuit. I installed a heavy duty spring loaded to off toggle switch on the dash for that function. The two parts together were FAR less than $80. Be sure to disconnect the battery before beginning a wiring project like this.