I worked at Nosler as a tooling engineer for 6 years. This piece looks quite familiar, especially the hopper/feeder mechanism. I do not know the piece personally but most machines like this were made and or modified by bullet companies for their specific needs. You may never find a manual for it, if one even exists.
The best thing you could hope for is a data plate on the cabinet or somewhere on the frame. That might get you a manual for one component of the machine. I would really doubt there is any manual for the complete system.
Where are you located? What caliber is it set up for?
The hopper/ feeder is for feeding in jackets/cups or leads depending on the design intent of the original owner.
I do know a machinist that built nearly all of the machines at Nosler and he could probably help you with the mechanical portions and even make tooling, but he is located in Bend, Oregon.
Nice machine. If you cannot find anything would you be willing to sell it?
Joe