Thank you all for the advice and pointers! Dugan is indeed correct. I unscrewed the rear standard from the tilt hinge and can get a better view of the bottom of it. There's a crack and the wood has jutted out at that point, causing the lower supports to be lower than they should. This appears a bit more involved of a fix than I thought as the lower standard connects to the side standards in a zig zag, comb-like connection. This might be a job for a pro given my limited understanding of these beasts, so I appreciate the recommendations.

I hadn't looked at the bellows yet as I didn't need worry about it until I could get the back on without it falling out. Will give them a thorough look through over the next day or two.

And thanks for the heads up on using an editor with cell phone photos uploaded here. I'm ironically mostly non-proficient in the use of cell phone cameras.