as it states, It would be nice to get a schematic for this PID
board or at least the OEM manual..

We have a machine that is full of these boards driving DC drives etc.

They are old tech but I would like to get a better understanding of the
controls on it.

It has Tach following adjust, Integrator, Int Rate, again, offset
etc...

But it also has some dip switches and other pots that currently seem to
be set to their zero place..

I can do a reverse engineer of one of them using a CAD app if I have to
but a ready made manual would be nice.

Fincor 105456401 or could be 10545640-1 and 1900-77 etc.