Good score! You may just need to clean and adjust the pump. On the line that feeds the site glass at the top of the column, there's a restrictor valve that adjusts the flow of oil to the top. May just need tweaking. Or the line it feeds has a blockage. See Figure 19 of the manual that I've attached.@akjeff , just found this thread. I just bought a Super 612 in pretty nice shape for $400. The oil pump is working, but not pushing up to the sight glass. I checked the "very stiff" tube, it is intact and clear. Where did you get the oil pump?
I bought my pump from Jim here. https://harigtechsupport.com/index-2.html