Ok so on the right side there is a z stop switch. If any of the side screws are moved when the machine is off,it seems that is the new location for either end. I have to turn the big verticle screws to keep the rails level. Especially since it takes alot of pressure to get prints off the surface, i am readjusting them every time. Is this normal. Is there another screw somewhere to tighten and keep this from happening?