Thanks @labcab, I see that channel leathers hooked onto. Looks like a bear to stretch & hook back on when I'm done.
Are there any snaps or screws hold on plastic once I get leather unhooked?
So I'm thinking; if I unhook the bottom, I may be able to pull on plastic enough that whatever's rolling around in there may fall out. Does that sound like it will work?
Yep. That's why I went in there and what I did. I was able to get out the junk rattling in there by removing one side from the channel.
There are a bunch of screws. ~10 holding the plastic panel to the frame a handful of others.