Product review (5 stars): She Bang She Bang No More!
This solved the problem of the agitator coming loose and banging around with every spin cycle.  This seems to be a design flaw with this washer. It's the second time I've replaced this part.  The current replacement seems sturdier and more secure than the last, however it's a bit harder to take off to remove the lint.  I'm happy not to have to run from any corner of the house to quell the banging and I'm crossing my fingers that the peace lasts.