I've got the same machine.
Do you lube your rails at all? If they are dry try some light machine oil and test again.
With the machine powered down, wind all the axis's for full travel both ways.
They should all be very smooth with no resistance. If you feel any binding, investigate that.
I had a Y axis ball screw that was binding in ONE direction only. I had two bad bearing blocks and I found bad misalignment in the Y axis bearing mounts.
All smallish problems but they all added up to one big problem. Don't stop if you find one problem. There may be more.