I just went through all this with my 1250. Turns out that the condenser wire had a TINY bare spot and was grounding out on the points box in a spot that was not visible until I pulled out the condenser a second time... and did a very close inspection. I decided to replace everything again that was just replaced two years ago, coil, plug, wire, points and condenser and problem gone. I'd double check for a bad wire and also for a short between the points screw and the rest of the tractor. There's a plastic insulating spacer in the bottom of the points box where the screw passes through. That insulates the wire to the coil from grounding to the main body of the tractor. If you get any continuity between the tractor and that screw then there is a short somewhere. I've never seen such a poor design in a tiny box as Wisconsin did with this setup. It's so hard to get all the pieces in place in that tiny box. Other than that it's a great engine and design good luck with it.
Thanks Husky...............still working on getting it figured out. Condenser wire was fine but replaced it anyway but with the same result.
There is an oily substance in that little box with the points and condenser so I'm gonna get that cleaned up and see if it makes any difference...........almost ready to do what you did and replace it all.