First of all he's only missing 2 fingers and he still has one of his thumbs. Side's that it was the thumb he lost to the sawmill, not a finger.
The one finger was a drw knife and the other was the drill press, 'sides that with the drill press he had to drill it three times before it fell off.
Lectricity won't work, member the lobster is steam and that destroyed all it's nerves, shockin' it would just destroy Slim's nerves.