I have a B&D electric mower that the switch failed the same way, I replaced it with a mosfet and that worked until I upgraded the batteries to LiPo packs, the ESR was so low that the inrush popped the mosfet. I'm making a new control now using an attiny microcontroller to PWM soft start it, hopefully that'll work better. I used a gas mower for years but my yard is so small that it's ridiculous, I spend more time cleaning out the carburetor than I do mowing. Seems I'm always having to go get fresh gas too, for a small yard electric is hard to beat.