Comment by ssl-3

My battery-powered lawnmower died once.

After I took the handle apart and undid some connections, I diagnosed it as a bad switch.

I fixed it by making a small hole in the switch body with a hand-held drill bit, shaking some water out of it, spraying in some Corrosion-X, and exercising it while watching its performance improve on my meter.

In terms of cost: It took about 40 minutes to get from "WTF?" to "Fixed!", along with maybe 3 cents of the magic spray stuff and some tools I already owned.