May I make a suggestionIJ  I had trouble when we first got our 1998 R42 two years ago.  I would be running in the field and lift the head, or change a setting with one of the switches that open or close the hydrualic selenoids and I would loose electric power, in the whole machine. Including our yield monitor.  It was worse trying to use the Auto Header Height control.  With suggestions from this site, I checked grounds. I found the common ground under the main console in the cab, was  1. loose, 2 rusty.   (you have to open the right side cab window, and take off the console panel facing that window to get to it)  I removed all ground wires from the stud, cleaned the area to bare metal with a dremel tool, and then put it all back together.  Things worked much better.  As I went along through that harvest, I went to every ground on the machine and did the same thing,  I found quite a few ground wires were on top of the paint on the machine.  I also added a ground wire to the hydraulic selenoid back to the machine structure itself. Also check the big ground wire coming off the battries   Since I did all this, I have not had any more trouble in the electrical area.  Hope you have a good harvet.