Does not carve at the same depth across the board

I am having a problem with my machine carving deeper on the left side, than on the right side of my project. I used a level to make sure my wood was level. it is level. I am getting exasperated with this problem. I am trying to carve my firehouse a flag with a fire symbol on it. I have had 2 flags ruined, and wood is not cheap. Any ideas???

Level have no meaning as an Xcarve mounted in the ceiling or the wall would still carve right if set up right.

What matter is that the spoil board is parallell with the X/Y plane, that the bit distance to the board is even across its surface. It will never be precise out of the box, not on “any” machine.

Use a spacer underneath the router bit to check uniform height across the board, you will most likely see some degree of discrepancy. To counter this first shim/support the board to take most of it away.
For maximum precision add a 2nd layer of spoil board and perform a “skim cut” of it.

Keep skimming it untill the entire surface of the 2nd layer is touched.
Your Z is now parallell to the X/Y plane.

Thank you. I will give that a try.