Have you tried both high and low? I would assume only the high is burnt out which means you need a new element and they are east to change I just did the same one on my 13. If neither work then I would take the throttle assembly apart and check for power there on both high and low side. If no power then take apart the other side that has the warmer switches in it and check for power there. If you search you can find wiring diagrams for your specific machine online and that takes any doubt out about which wires do what. Also, if you haven't yet I'd rip the stupid foam off the back of your thumb warmer and cover that whole board and wires with epoxy other wise that will need to be replaced soon as they are junk. Good luck!
Yes that's how mine started out and now both sides & thumb don't work. Sometimes they would work and then quit but nothing now. Fuses are good & checked controls and no power to there.