Happy Father's day everyone. Ok, I'm trying to help a friend get his "new" mill running. It's a Wells-Index mill 520/CEN/5 with a Centron M400 controller that was purchased at a government auction. When He first got the mill, the only message we got on the display was "clock c-mos battery low" but after replacing that chip on the cpu board (AR-B1564 - ACROSSER) but now the display is just blank. With a choice of 3 main systems boards in the system (CPU, Display / keyboard control, and servo motor controller board) and not being sure if any of them are "good", I need a starting point to trouble shoot. I've checked all of the voltages / power supplies and connections. 3.5" floppy drive is working fine. So, my question - Does anyone have one of the M400 control modules that you would be willing to install our CPU board into to see if it's at least running at all??? I live in Northern California (Sonoma county wine country). Thanks for reading - Dave Harris. p.s. I've also posted this in the Wells machine sub-forum.