[Jared]

We've used 16 pitch worm gears twice now, and we highly recommend the bronze worm wheel over the cast iron. The part number for the bronze is (from martin gear, not boston gear) wb1620. We had a few cast iron ones fail in 2013, but no bronze ones. We drove the bronze 1:1 with three CIM motors, so we saw, at most, 3x CIM stall torque. You have a 1:7 reduction on the CIM, so you could see up to 7x stall torque, so I would be a little worried with your setup, as I remember we were slightly above the max ratings at stall.

If you have room, you may want to try heavier duty worm gears.