Update - removed 4th axis board (A20B-0008-0470) from control cabinet leaving only alarm 424 y servo. The machine has inductosyn scale feedback, and after some digging a broken wire was discovered in the Y feedback circuit. After repairing this the machine will come up ready and can perform zero return for X,Y, & Z. Is it normal on these machines to have to hold down interlock to get any of the manual mode buttons to work? Why does the A axis still come up on the screen when the neglect is on and the board is removed? There must be another parameter deciding how many axes the machine has? The machine will not execute any commands in MDI or memory making me think the control is waiting for the A axis zero return before it will do anything. Also the tool changer doesn't respond to any of the buttons (such as origin which is required), but all mechanical functions work via manual override on the ends of the solenoids. Not sure if this is a result of the homing sequence not being complete or if that is a separate issue. Once I get the basic 3 axis machine running I will be building a 4th axis to work with it. I would love for Al the man or Dan Fritz to chime in with their wisdom and expertise!