Fifth wheel questions

keep the knob pulled out for normal operation , if storing for a period of time without shore power connected ,push in to disconnect the battery otherwise you will drain the battery from parasitic drain.
Keep in mind the inverters are bought bulk and cheap to the manufacturer ,the more load you put on them the harder they have to work, hence little dimming and maybe flickering.
You could all ways check the connections to make sure all is tight, CAREFULLY or with all power disconnected and tested.
If you plan on keeping the trailer you could all ways up grade to a better inverter.
You could all ways pull the panel cover off and see if there's any 12v wiring to those fuses . No wiring /no fuse ect, if there's wiring try a fuse and see what it works and label it.

ok thanks, see I have been keeping that knob pushed in this whole time, which I am guessing is a constant feed to the battery, and maybe thats the problem. But wether its pulled out or in, the lights still flicker and dim, we use the trailer just about every weekend in the summer and it hasnt gone bad yet, but maybe the inverter is on its way out.

I also was messing around in the fuse box and like fuse 11 or 12 there isnt a fuse but the right light on it is always on, put a fuse in that slot and everything turns off, so I am guessing there shouldnt be a fuse in there, unless I have something wrong.

our 07 challenger 29 trl was actually 35' 3" and I replaced the inverter because it actually failed completely on a camping trip. But it acted the same way before it failed. That nite I hooked up a battery charger to the battery which back fed the system and all 12v was good , had to keep fridge on ,and so on.The next day I replaced the inverter and life was back to normal.
That little knob must stay pulled put for normal use , that is the battery disconnect.