I don't know how handy you are at making things but if this happened to me, I first would look for a used switch on Ebay. If that did not work I would probably buy a micro-3/way toggle switch and remove the guts of the old switch and wire in the toggle switch. You could make a simple aluminum plate to mount the toggle switch into and use some 3m extreme double sided tape to mount the plate to the hand switch assembly and cover the hole from the old switch. I think you could make this look clean enough to be acceptable. I also would get a waterproof toggle switch cover to put on the switch.
Just a thought.
Just a thought.