Followed this with interest because I have an HD850 - which is exactly the same with a slightly smaller skip.
Mine has been pretty bombproof for the last 3 years or so
Guess I've been lucky with water getting in so far - taped over those blank holes on the dash
So, to fix the problem was it simply a matter of drying out the control board?
Few things to do to mine this year:
Paint job; new tyres; find and fix hydraulic drip from one of the drive motors
BTW - I have all the manuals if you ever need further information