Vcore4 IDEX 400 t1_y Resonance Graph Wildly Different

Does anyone have any suggestions on where to look for this. My t1 y resonance graph shows a large offset between the x and y lines. I have no idea what to change, as all my other graphs the x and y mostly line up vertically. I did check the gantry moves to the back where both sides touch the motor cages simultaneously. No matter how i tension the belts, the t1-y always has offset x and y curves.

Any idea what could be the problem? I checked nothing is loose and the belts are roughly centered on the pulley (the belt seems to be manufactured not exactly straight so it does ride up and down a tiny bit touching the 20 tooth pulley lips depending on where the print head is))

Any ideas of where to look/ if I have mechanical issues? Thanks