Stuck, considering rebuilding VC3.1 500

Printer sat, then was moved into basement, then sat some more, and I’m recommissioning it. I can’t shake this mesh, where the back is falling off the whole way. Z tilt doesn’t seem to do squat. Shimming the feet doesn’t help. After the mesh, z tilt is still reasonably within range (.03 vs .015) so it doesn’t seem to be stepper issues. Help me Obi Wan Kenobi, you’re my only hope!