Help testing and repairing Thomas rotartry vane vacuum for my molder...

I inherited these two vacuums and I'm trying to get one good one from the two. The one on the right was totally frozen. I suspect the surface rust has ruined it. The one on the left works, but it doesn't seam to be pilling much. There is air coming from the outlet when running. I need a rotary vane vacuum pump 101 course. Can anyone shed some light on these?

Thomas Model TA-0075-V Part 991091

Attachment 235324

Well I finally found Welch bought Thomas and they repair them. I'm waiting to see the cost of repair. What are others using for a high vacuum pump? Would it be worth the trouble to make a reservoir for the system with only a 15" x 20" table? Help me people I need to get this system working. :D