[weedhopr]

My 1541 has been having ignition issues this spring. It starts right up, and runs great....as long as I keep it running. Several times, I've shut it off, and when I tried to restart it, it wouldn't fire...found there is no spark.
I thought it was an intermittent connection at the ignition switch, as once while troubleshooting, it started to spark when I wiggled the wires at the switch, and started right up.
The next time, it didn't help. I cut the mag wire, just before the engine connection out of despiration (to eliminate any problem in the tractor wiring) and there still was no spark. My thought is something in the ignition system, inside the engine.....the next day, after work, I tried, and it started right up.
What would be the most likely cause of my intermittent problem?
(when I check for spark, I have the spark plug wire connected to a plug, clamped firmly to ground, never operated without the plug wire connected)