Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! Never changed arm switch on a ZD21, but looks lie they bolt to the frame, under the fenders. If you can't access the switch to replace it, looks like the fender covers needto be removed. But before you do that, take some WD40 and spray the switch down and work it manually to see if it will free up!