Some of these plastic blower wheels are seized on to the shaft due to moisture getting into the shaft area. If the blower wheel is scrap anyhow you may have to pull hard on the edges of the wheel to get it off. Sometimes they break apart at the hub area . Most of the ones I have taken apart are damaged in the hub. You mention this is a repeat replacement. Did the previous one have a damaged hub ? I find some of the new blower wheels are not very uniform and as they rotate they wobble a little. I always make sure they are not rubbing around the edge inside the blower housing .