[Pick]

Well, to start with, in my opinion, you should have kept the Jordan. With it's built in ammeter, it can tell you a lot. Now, with 6 brake magnets, and the Jordan set up properly, you should have been drawing over 18 amps. You said you adjusted the Jordan to it's lowest setting and it read 5 amps. That would be less than 1 amp per brake magnet. Brakes should not have been grabby at that setting. Not familiar what "3.5" means on a Prodigy.

You said the brakes were checked out and adjusted TWICE. By whom? It seems to me that they are still out of adjustment. Are you sure they put the right backing plates on?

My guess "over the wire" is that they were never and are still not adjusted right. Very hard to diagnose without being there, so this is my best guess. Others will chime in with their thoughts.

Did they machine both the magnet and drum surface of the drum that was not replaced? That could be a potential trouble spot.