My 1987 GM 4.3L.OMC stringer with mechanical shift had been starting fine and out of nowhere, it has suddenly developed this problem. Sometimes when I turn the key it does not start, no click, nothing. If I monkey around with the shift cable at the engine where the neutral safety switch ( I think that is the name of it) I can sometimes get power to ignition again and it will start. This is an intermittent problem that is absolutely driving me crazy!! My battery is fully charged , I have removed and cleaned all the battery cables, ground and everything , the ignition switch is new but I tested it anyway and it tested good. I jumped the selinoid to ensure it and the starter were good and yes it got power and cranked over. I don't know how to test the shift interupter , electronic shift assist or neutral safety switch whatever it is called on this boat. Please throw in your 0.02 cents any help is appreciated.