I've never dug into the wiring bundle going through the top of the hatch on the 80 but it does sound like you have eliminated the switch and the relay as the problem. I did repair a washer hose in the top of the hatch on a 60 once. That was way more work than it should have been.
'03 KTM 450EXC
"If you know what you're doing, then you aren't learning anything." - A. Lincoln