Bed Levelling Issue

I have a new Taz Workhorse, and I have been having adhesion issues in two of the corners.

I attached a dial gauge to my head and ran it around. The Left Front - Right Rear diagonal is all within .002". But the two other corners (Left Rear and Right Front Front ) drop significantly. .014" for the LR and .009" for the RF. (I have cleaned up the head and the levelling seems reasonable)

If I set the offset for the bed to -.075mm and this gives me good adhesion in the center. But at those two corners it’s spotty.

If I adjust for the bare minimum good surface at the bad corners, the ridge diagonal is smashed.

I have been reading about how the bars may sag, but wouldn’t they sag in the center of X?

Can I shim the glass? is there a good way to deal with this?

Here are the measurements (0,0) is the front left of the plate:

[0,270] -0.014            [130,270] +0.002          [270,270]  0.000
[0,130] +0.002            [130,130] +0.000          [270,130] -0.002
[0,0]   +0.002            [130,0]   +0.000          [270,0]   -0.009

Here’s what it looks like at the BACK LEFT corner: