Old VDF without manual, any chance?

https://preview.redd.it/ts4hehqzwyce1.jpg?width=1816&format=pjpg&auto=webp&s=bd8925073ede1ccf1fd1790c0732925b8e36ce2e

https://preview.redd.it/pn0evhqzwyce1.jpg?width=1816&format=pjpg&auto=webp&s=b8e78653e7bab8c7b2027e4cb986d0e9a021c108

I have this old VFD installed on a 25 years old router, where should I start? I'm taking any kind of advice. I'm on a steep learning curve on retrofitting this machine with Linuxcnc, I have 3 axis working but I'm behind with the electrospindle part of the machine..