Hey Chief,
I think you are approaching this correctly. However, look at where the plate meets up the slide walls and look for witness marks of where the nuts/washer have possibly moved during travel (maybe nuts weren't good and tight). If so, than use a floor jack with some lumber and move the room as needed (back to original witness marks). If you don't see anything that indicated the room has shifted or dropped.....I'd start looking for something bent or maybe call SC for further advice.
BTW: 53 cases of OP in the slide will make the room flex a bit!

Always gotta get my teasin' in........
Please let us know what you find out.