Believe it or not, the data for all of the gauges probably comes from engine area of the coach to the gauge area of the coach on a single pair of wires. The CAN (controller area network) that is used by the engine, transmission and chassis manufacturers allows data to be shared on a common bus.
I cannot speak about how Newar handles theirs but Freightliner has a box which is essentially an amplifer that hooks to the main wiring harness in the back. There is a connector there. In the front of the chassis, there is another connector for the "spider" harness that is individually laced out to each of the gauges. Provided that they are the same size (like the tach and the speedo) I can physically swap the connectors on the back of the gauges and each gauge continues to function normally. My guess is that Newmar uses similar wiring components.
How to I find out all of this? I had a highly intermittent speedometer problem that Freightliner was unable to fix in several times. Finally, I fixed it by concentrating on the connectors, not the components. I worked on mainframe computers for many years and my experience tells me that it is usually the mechanical (i.e. connectors)components rather than the electronic components that fail Particularly when you have something that works, then doesn't work, that is a good sign that it is a connection. Were I troubleshooting your problem on my chassis, I'd try to isolate the failure points to either end of the main chassis cable and to the two CAN data bus leads in it. There is usually a diagnostic connector which allows the tech to see the same information that the gauges see but it is displayed on a computer screen. In my case, the diagnostic connector is right where the spider harness plugs into the main harness. For your exact kind of problem, I purchased VMSpc which plugs into the diagnostic plug and can display the day on a computer screen the same as the tech can.
There are not many shops that have techs who are good at electronics, particularly at connections. Having them swap components, even under warranty, is probably not going to solve your problem for very long.
2000 Georgie Boy Landau 36' DP
2005 Saturn Vue toad