The red wire 12R is hot all the time. Jump from red wire to the following wires. DBL 12 that is the ignition 1 run. The 12 BR is ignition 2 for starting. Understand the Brown wire is for full voltage to coil for starting only. ( the brown wire is the one I suspect to be the problem. ) You can try just using the Dark Blue ignition 1 it might give enough power to the coil to start. Also apply power to yellow 12Y that is for the starter relay for starter to turn over and start. You could put the yellow and brown wire on the same switch because they both do function at the same time. It's a momentary operation.
You can use any switches you have there is no real high current for thesis circuits. If you have a house hold light switch and wire nuts can be used. Understand ( you probably do ) the starter switch yellow and the brown wire switch need to be turned off once it fires up
You can also touch the wire together if you can manipulate every thing.
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