I have a 1975 JD 400 with a briggs 23 hp. The wiring harness with the diodes for the coils attaches to the side of engine and they end there. There is a tab that can be plugged into but there's nothing there and I'm guessing that is the ground. My problem is that when I shut off the ignition switch the engine continues to run 5-10 seconds then shuts off. If I ground out that tab with a wire to the frame when I turn ignition switch off then it powers down beautifully. IF that is my problem then can I wire that tab back to the ignition switch? My ignition switch has the 5 pin with letters B,S,I,R,A. I'm a novice mechanic but I have no electrical skill what-so-ever and our local shops start out by charging 35ph. I'm at a loss here and I'm hoping you can help, I appreciate it!