I watched a YouTube video of your make, model, and year to see what you were up against.
Here's the video starting at the spot that shows the slide and shower together:
https://youtu.be/cpVjp8jitug?t=805
If you are trying to remove the facia, it's held on with a million staples. You'll just have to pry it off. Once off, pull the staples completely through from the back side. This way, you won't have holes and scaring on the front when you replace it.
I'm not real sure what you mean by "cover". Is there a cover directly over the pully, or are you referring to the facia "cover" with the million staples in it?
If you are trying to remove that plastic long piece that runs up and down covering the actual cablers, well .... good luck with that one. I never figured out how it comes off. I just pulled it out of the way and used clamps to hold it so I could work behind it.
Here's what mine looks like (front living room model, front living room, passenger side (left end as you stand in front of it inside the camper)
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2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually