Have you considered replacing the drum with a rotary switch and some contactors? It has many advantages. Maintenance, availability, cost, easy placement, flexibility...
You should be able to get your machine shop to make the contacts. I would stick with the drum contactor. Keeping the drum contactor may end up costing more but the nostalgia would make up for it.
There are several companies that still make and sell parts for drum controllers. Torresdale, Inc. and MaCabe Electrical Conductors are both in Pennsylvania. Hubbell Industrial Controls also makes complete drum controllers for retrofit applications