I bet I know what he did.
When putting the plastic part that hold the magnets (vertical) make sure its setup up in a Cris-cross config. This should allow you to move the top and bottom independently. When you spin the two apart and hold the top stationary , the magnets should pull/spin the bottom ball carrier toward the feed neck ie preloading the balls. I accidentally put the magnets on the wrong side and this would apply direct tension to the ball stack with no magnetic cushion/feed.