We have an Arrow 500 that sat for a couple of months. When we went to use it recently and pressed the align button all axis jogged and the display shows x0 y0 z0. How ever when we try to jog the carousel to the spindle it gives the alarm "Z axis too low". I believe there is a switch at the top left of the z slide that must be made to let the carousel swing into position under the spindel. The "z" homes 1/2 to 3/4 of an inch shy of this switch. How do I reset the home position, what tells the machine where home position is? Thanks for any assistance. Brian