I purchased this part to save money for an elderly customer . It would of been easy to test by blowing down the fitting and hearing the turbine spin. Fortunately I plugged it in the boiler wiring and blew down it and the boiler didn't respond,this is what I did before stripping the faulty original out.
So I bought a new Vailant turbine and job done..
Seller as initially offered to send a replacement .
Brilliant product, came looking like new with speedy delivery. O ring and fibre washer supplied as well. Fitted and worked perfect for a fraction of the cost of a brand new one.