Nice old drill. Can't see from your photos if it has trip clutches to raise and lower the openers or if there should be a hydraulic cylinder to handle that operation. I restored a pair of Minnepolis Moline P3-6 drills (10 ft wide, 20 drops, 6" spacing) a few years ago. One of them had the trip clutches. The other was hand operated so I rigged up a hydraulic cylinder to raise/lower the single disc openers.
Good luck in your restoration project.