Project Sheet Cake was used as a reference:
https://code.google.com/archive/p/sector67-sandbox/wikis/ProjectSheetCake.wiki
Linux CNC was used for the replacement CNC controller:
http://linuxcnc.org/
This was rewarding, but also a bunch of work. 90% of the work was wading through wires, old documentation, and understanding how CNC's operate.