[Farmall] M magneto trouble

[William Ransom]

When I thought the magneto needed a new coil (as I mentioned in a message I sent a while ago), I took the magneto apart. I bought a point file and filed the points, and, after that, I got it to spark, so apparently the problem I thought was with the coil was actually a problem with the points. When I first put the magneto back together and back on the tractor, it seemed to be working properly. I removed the #1 spark plug and put it on top of the oil filter. I then turned the power-takeoff, using the front section of a PTO shaft from a Fox chopper for a hand crank. When I did that, the spark plug sparked every fourth time the magneto clicked, as it should. However, I tried the same thing a while later and then the spark plug sparked sometimes, but not every time it should. Now, I can't get the spark plug to spark at all unless I connect it directly to the coil, where the coil wire belongs. Then, it sparks every time the magneto clicks. Since the spark plug sparks when connected directly to the coil but not when connected to the distributor cap, I think the problem must be with the cap or rotor. Do you have any idea what to do about this problem?