But not when its at rest in the middle .
I'm a bit confused here. We have an '04 Itasca Horizon 36GD with the CAT C-7 that's almost identical to your coach. And, with our dash switch that switches the power to the radio from coach to chassis batteries, there is no MIDDLE position. It's either flipped one way, or the other with no stopping position in the middle, like some toggles.
As for "Cutting" any wires, I'd pull back on the reins on that. Winne put all the wires in that operation that are necessary for that radio to operate, in two different modes. You DO have a problem somewhere but, cutting wires simply 'cause you haven't located the source of that issue, is not the way to solve problems.
I do agree that sometimes Winne's wiring diagrams can be a like following a Los Angelus CA road map, a pain in the a$$. There are some pretty good folks on IRV2, in the Winne section that are good at reading those. If I were you, I'd cruise on over to that place and see if you can find help there. Good luck.
Scott