I just ordered my third ANOVA and had the same problem with the other ones.
There is a simple sollution by bending the upper rim of the tube, to a slightly oval shape.
Don’t overdo it! Just smoothly little by little with your flat hand.
This method works perfektly.
A response to a 2018 post however this ‘fix’ might still be relevant to others searching for options for fixing a loose stainless steel sleeve (mine caused by the plastic body warped/deformed by heat, crazy right?). A cheap Euro 1 clamp over where the body and sleeve meet seems to hold and align the sleeve with the body, and the impeller not longer knocks against the sleeve. ref. pic
