I found that my UP! Mini Bed support was slightly too high causing my bed to be high in the center. So I drew UP! an array of supports in slightly different heights to swap out to get it to the right height.

The standard height from my stock part I measured was 8mm.

1 - Download all the parts of different heights. 2 - Place them on a bed and print at 0.2mm on fine. 3 - With Perf Board in place measure bow of the print bed. (mine was 0.4mm) 4 - Disassemble printer and remove factory part. 5 - Replace with part of approximately less height.