Sometimes, the old controllers are just plain worn out. DH checks them and finds the contacts that the finger moves over are worn and not making good contact. The Nichrome wire breaks and the old controllers get too hot sometime. We prefer to replace them with the with the solid state controllers from Sew-Classic.com for under $20. They are on sale for just under $17 right now. IT IS THE BEST MONEY I EVER SPENT. Intend to get one for all my old machines. I have one on the FW and it saves a lot of carrying weight. They are much lighter. After using one, there is just no excuse for the heavy, Ceramic type with old time technology. You can save them, if a purist wants to put it back someday, but to use, you can't beat the solid state type. My back and shoulder don't have to tote the heavy things around anymore.