My Series II with Hed. Tnc 150 control, spindle wont start.

This morning, when I would use M25 to send Z up for tool change, after the spindle moved up, it would not complete the move, so I adjusted the little nut (at the bottom of the rod that runs up to the switch at the tool change cylinder) so that when the spindle stopped going up, the switch could be made. So, now that seemed to work fine for about an hour, then...

When I give it a M3 or M4, it just sits there with that little "*" symbol blinking, and I dont know why it wont start. I can power down, back up and it might work a time or 2 then quit again. Any advice appreciated!!