"I just went through three weeks of frustration fixing this machine
tool. "

I've found that usually corrupt data is caused by the circuitry, not the EEPROM itself. However your unit is old enough it may have actually failed. When things get old, things get weird sometimes. You see extremely uncommon failure modes and sometimes those "gremlins".

Where I used to work they bought an EEPROM copier cheap. Maybe twenty bucks, but it could not do everything. It did what we needed but it did say that certain types of chips need to be erased before they can be copied onto. The ones in the equipment we worked on did not need to be erased.

These units have a mechanical power switch, so I suspect that sometime the corruption is from turning it off at the wrong time. They are Karaoke players and usually the USB and SD puts became deaf dumb and blind. I had a whole set of them with good data to copy from.

I am somewhat surprised you found a used board for that thing. But since you did you probably should copy the data to either the old EEPROM or a new, compatible one for backup. If it happens once, it can happen again.

I really hadn't heard of that brad of lathe, but if it has Timken bearing, hardened ways and all that it is probably worth keeping for life. That is if you have a use for it. I used to have two lathes but then realized they had been used maybe once in five years I sold them off. Plus I need the room..