...sounding like a possible PS problem.... one problem the Delta 40-60 CNC series controllers that I have read and seen in the past is AC Ripple is to high on the DC Outputs..... How comfortable are you with using a Volt meter on Live wiring? Because, we need to check the 5vdc, +12.vdc, -12vdc, and 24vdc outputs from the D50MU PS. There are some Test points inside the PC Case.
https://www.dynapath.com/services-faq2.php
Did you get any Autocon/Delta manuals with the machine? There are two..one for Programming the PLC for machine tool builders and one manual for Operation..
....one more thing we should do is backup your Parameters and the PLC EXE files....is your FDD working? Also could use RS232C port#1
DJ