Won't start hot - Magneto?

[wordmachine]

49 Cub 6V positive ground with magneto - Won't start hot
Well, I fixed the starter(hand starting all summer), retimed the engine three times, plugs, points and condenser, tried
a 6v coil from napa. re timed the engine and then it ran.. Now it won't start again when even slightly warm, which was original problem..
I guess it is the magneto, but up for suggestions. I have a 6V coil on hand , but not sure if + and - get switched since it is positve grounded.
Any help would be greatly aprreciated since I have fields to disk asap

thanks
MIchael

[Eugene]

Top of page, manuals. Free down load. The operator's manual has photos of the magneto and the battery powered ignition system.

There is a 3rd type ignition system where the magneto's coil has been disconnected and a car type coil installed. This system is battery powered.

Need to know specifically which type ignition system your tractor has.

Have you checked the ignition timing with a timing light?

Suggest compression checks and check/adjust the valve tappet clearance. Basically, I'm headed towards a complete engine tune up.