Not much help, but a big hello.
When setting up a frame, you have to be super level and square and plumb. My friend's house had some sort of dip in the floor boards under the carpet and try as we might we couldn't adjust around it without a little square of cardboard.
Another thing to check are the encoders, make sure they are clean and properly placed. If you notice the machine will stitch well in one direction, but not another that's usually the encoders.