Hello @mwbeard1957 and welcome to the forum. You mention the Y dimension is correct but didn’t say what the X dimension of the oval is.
Is the oval longer along the Y axis like the X axis is not moving enough? If so you may want to check out this post by Sienci. They mention a couple of things to check with the X axis if that’s the issue.
When I assembled my MK1 30x30 I didn’t get the motor to lead screw coupler tight enough and the X axis would slip under load.