Pete, Lawnboy designed it to have a kill wire - you just need to get it working the way they intended. There is somewhere between the moving breaker-point and the strange rotating switch, where it is touching ground due to a fault in the insulation of the wire, or the rotating switch itself is defective. Just examine the wire, and take a look at the switch. You'll probably find it easily. If you don't, you could just run a new wire to a simple toggle-switch, but fixing it is better than redesigning it.
It's best to have a kill switch, both for safety and convenience. I have had lots of mowers without one, and I've never actually used a kill switch on a 2 stroke mower because I like to put them away with an empty carburetor, but if I were you I'd be trying to make it work the way it should just to keep it original. As an extra benefit, Lawnboy did a lot of development work to get it to work properly - if you redesign it, you have to expect teething troubles before you get to the standard you want
