Dave, I recently repaired the left side, outboard end of the fuel tank on my 415C by following the instructions on the link below. It worked great and no leaks at all! After I removed the fuel tank. I ordered up a bunch of the rivets as descibed, drilled out the old, cleaned things up, redimpled the holes,placed fuel tank sealant where needed, installed the thank end, and riveted the tank end back in place with my rivet squeezer. Afterwards, let it dry for a day, and them pressure checked the tank with air and soapy water. If you decide to fix the leak yourself, let me know if you have any questions.
Kind Regards, Stan Bearup American Falls, Idaho Here is the link: http://www.ercoupe.info/?n=Main.TankRepair
