My Pilot Pro with Mach3 was working OK, but now if I try to jog the Z axis either in MPG mode or y the keyboard (Page Up/Dn) the Z axis sometimes moves the correct direction and sometimes moves the opposite direction. I can press the "Page Up" key and the Z axis will move up once or twice then the next time it will move down, if I keep pushing "Page Up" it will reverse direction - I neve know which way it will move. -- Any Ideas?