I own one like yours, and ran one at work for some time.
If your spindle is not retracted above the home position, the tool will not be released. At least the machine at work has a hand drawn line about an eighth of an inch above the Zero line, marked as the tool change position. Can't move the spindle up unless ypu pop the belt off the servo and hand-bong the ballscrew around to move the spindle that little bit higher so the balls will clear the pull stud.
Two batteries to look out for. The CMOS battery on the motherboard and there is another one on the SimDisk board as well, IIRC. I dealt with the latter, on our work machine a while back, and it went reasonably well. Until the SimDisk skipped a groove a blew a trace on the card, in any case.
Milltronics emailed me a copy of a workbook for the conversational programming for the asking. Maybe worth asking them if they can send it to you.