How do you access the furnace in a 2018 Pinnacle 38FLWS. The propane furnace in our 2018 Pinnacle 38FLWS will not dependably light. The fan comes on but it does not light every time. I replaced the thermostat but that did not help. I think narrows it down to the igniter or the sail switch. One time when it did not light, I could smell gas therefore I suspect it is the igniter and not the sail switch. There is no discernible outside or inside access to the furnace. How do you access the furnace? Any input is appreciated.