Hi Brian,
I so far have been unable to trace a circuit diagram or instruction manual. First thing that comes to mind is to do some basic checking such as the plug and the control box to check for wires that may have become loosened be causing a short, beyond that I really don't know where to look.
I am fortunate that I have the CNC mill and it is easy to use, it's just nice to have a manual mill as a back up or spare in case I need to keep something on the CNC mill table.