Turns out Im an idiot, my 7xl wasnt dead. I hadnt ground a flat spot on the shaft, so the pinion setscrew cut a ring all the way around the shaft. I saw that the motor was revving but the pinion wasnt moving (even though the set screw was tight), so I assumed it did the same thing my 380c did. So now Ill probably wait till the mmm comes out before I do anything different with this thing.