Thanks for the responses. We've plenty of 220v 3 phase power.
The problem was that the coil (464-2) in the starter box was too weak to engage the switch, or something else wasn't cutting the mustard. The motor would turn lethargically for a few seconds and then pop the breaker. The other problem was that we hate wiring things.
One leg of power goes up to the start-stop switch and then back down to the coil, where it happily joins the rest of the power if the switch closes.
The thinking was that the coil was meant for 440v to go into it and not 220. Someone theorized there must be a "464-1" coil out there that could help us. I was tasked with finding one.
Research into the matter on
another thread in the forum , about getting a Monarch 10EE going, seemed to reveal that the 464-2 really was the correct coil for 220v 3 phase power to a Cutler Hammer starter box, and that 440v coils were type 404-3.
The other knuckle buster claims to have converted the 5 hp over to the low voltage configuration, per the series-parralel diagram. But now I'm thinking this thing might have been running off 220v back at MIT, and maybe my partner only reconfigured the 5 hp back to the high voltage circuit.
So there's something else going on in there, probably. I'm not the one doing the wiring (what with my erratic habit of referring to 220v 3 phase as 110v single and all that's probably a good thing) which adds to the confusion. When we get it spinning I'll post and tell you what ended up being the trouble.