I understand your frustration and I'm with you on this. You will need to read above and answer all the questions or I can not help you. I am not there. I'm at my house. I can't see it. It is probably simple once I understand what you have. There are several questions in my last post. Please answer each one. I have not asked you to trouble shoot. I am trying to do it for you.
I am guessing (which I hate to do) that you have a 6V system with a coil that needs no external resistor. I'm guessing the motor may be a car motor with an electric solenoid and a spring loaded V8 ignition switch. I'm guessing the switch, or it's wiring, no longer has a circuit for energizing the coil during crank (far clockwise position of switch). It still does have connection to the coil when switch released ("on"/"run" position of switch). I'm guessing motor is still cranking a little (momentum) when switch released and coil is then fired to start motor sometimes. Arm chair guess: Bad ignition switch, loose wire, broken wire. solenoid "R" circuit.
If the system is 12V now, different guess. Will adjust opinion if and when I get more info. Nice to have Msrs. Lederman and HotRod Jerry's opinion and anyone else.
