vint-mow, I even ground the edges off the coil to see if I could get enough clearance (not sure if it damaged the coil but that doesn't matter as I have buckets of them) Problem is the PT coil is about 28mm thick and the F/C one is about 21mm so I am looking at a 7mm problem. Not sure what would happen if I ground the leg to allow the coil to sit back further
Sounds like more trouble than it is worth Norm. I am about to try Max's suggestion of reversing the aftermarket coil on the core. I am now convinced that this is the problem. They have made these coils to suit both internal and external flywheel setups, so for older coils you have to flip them.
A word of warning on these new aftermarket coils. The wiring is VERY fine compared to the originals and they have no large blobs of solder anymore to support the wires. I completely severed the connection between the coil and the spark plug lead screw on my coil by applying too much pressure when screwing in the lead wire. I've never seen or heard of this happening on the old coils. I had to grind down the plastic on top of the screw and rejoin it to the wire with a blob of solder. So you obviously have to be very careful not to screw the lead wire in too tight on these new aftermarket coils. Also the positive and earth wires coming from the coil are very fine and not soldered, so if you bend them back and forth a few times they will break off level with the coil. The very first thing I do on receiving these new coils is get the hot glue gun and add some big supporting blobs of hot glue around the connection points on the coil. It is not hot enough to damage the wiring. This will stop the wires from breaking off and totally ruining your day. I would think that just the vibration of the mower over time will cause many of these new coils to fail. But that seems to be the modern trend with mass production.
