Has anyone replaced the CO detector or the main thermostat? We are having issues with both. CO detector was already replaced once and would like to replace with something different. Thermosat will not work unless we tap on it. We checked all the wiring and still not working. Is there a better replacement. We have a 2014 36gk. Also our furniture is shedind really bad. It's looking like 5 years is a mile stone for redwood along with all the other problems along the way.

I replaced my co detector with the same off amazon.
As far as the thermostat I would unscrew it from the wall and check the connections as some have found loose wire nuts

We are one that had loose wire nuts. No issues with the CO monitor, and before I found the wire nuts I had already ordered a replacement t-stat. My understanding is it needs the same Mach Coleman RV Comfort in order for the Heat Pump and AC controls. Ordered mine from Amazon, one local parts dealer had a white one which I didn’t want. Mine was for the bedroom so it won’t help you but now I have a spare one.

I replaced our stat with an identical one in the spring after the stat defaulted to 72F overnight regardless of the set point.

It's been the "year of the furnace system", the main board on the furnace also packed it in, the stat clicked but the furnace wouldn't start, it's the second main board that has failed. I got a replacement for the stat and the main board from Amazon, cheaper than getting them from an RV dealer.

Cant help with the Co detector , but try looking for a loose wire nut behind it. I had a issue this spring I was able to cure by take tstat cover off and spraying inside the selector switches with wd-40 while sliding the switch left and right fast several times. Be careful to NOT get wd-40 on the wood ,it may stain it . My issue was it would not turn on the heat pump , its been fine since thankfully . The slide switches have covers over them that are black and sit inside he unit cover.

I personally wouldn't recommend using WD-40 in the sliding switches of a thermostat or any other electronic device. Electronic contact cleaner is made for that purpose. Wouldn't recommend using it on the 7 way bargman plug either on the truck or the end of the Redwood cord either. More of a chance to collect more debris and degrade the connection even further. Just my $.02

I personally wouldn't recommend using WD-40 in the sliding switches of a thermostat or any other electronic device. Electronic contact cleaner is made for that purpose. Wouldn't recommend using it on the 7 way bargman plug either on the truck or the end of the Redwood cord either. More of a chance to collect more debris and degrade the connection even further. Just my $.02

Totally agree!
IMHO WD40 is for rusted bolts & removing tar off your vehicle. NEVER use it on your rubber seals, use Pledge furniture polish on all rubber seals on your RV.
Contact cleaner for electrical contacts & if you like WD40 use the silicone one on anything around your RV.