there is a chance the impeller shaft got bent out of shape..
I heat tempered mine when I was using these..
a little nuts but it works..
try giving it a good cleaning first
also.. if they are not set just right in the housing they can rattle around as well.. but Im assuming you have tried taking it out and putting it back in.. if not give that a shot (if its clean)
if cleaning and multiple trys of reseating it correctly dont work.. take it apart and roll the shaft of the impeller across a flat surfase like a counter or table.. if it wobbles.. I would suggest buying a new impeller (these can be straitened but its a horrible nightmare of a pain in the rear, Ive done it a couple of times with a hammer and a nice smooth flat concrete surfase.. HUGE pain to get right)