CTC 3D Printer - Need help please

thingiverse

Hi i got my ctc 3d printer a couple of days ago. it is working really well. when doing anything with the Z axis but when it does x/y one of them is messing up and circles come out oval (top left and top right) of circle have a gap in them and wonky also when it prints form left to right. things have a small gap there aswell i've looked everywhere possible for a solution but coming up with nothing. Thanks