If this helps, here's what I do in this situation.
I have a jump pack with a pair of clamps, but you can do the same thing with a battery and jumper cables. Attach a small wire to the positive clamp by whatever method you want(screw terminal, wrap bare wire around it, whatever)--about 3 or 4 feet long, 14g or 16g is good. Attach the neg clamp to a good ground on the tractor.
Attach the small wire to the +terminal on the coil.
Then just touch the + clamp to the large terminal on the starter momentarily to start. Remove to let it run.
The small + wire on the coil and the ground clamp is all you need to keep it running. Hope that makes sense.
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