I have an old Forney welder that had the capacitor cut out of it when I got it. I can weld fine at higher amperages, but have trouble starting an arc at lower settings. According to a source on the internet, a 20 MFD 370 volt motor run capacitor should be a good replacement. I can order that capacitor, but already have a 45 MFD 370 volt motor run capacitor laying on my bench. What would be the consequences of trying the wrong part in this application? If it is just a matter of it might not help, I would give it a try, but I would hate to blow up the cap and possibly damage something else.