Photo is the 8hp impeller. I could see daylight between the metal hub and the rubber. I am certain the rubber was at least occasionally slipping around the hub. A good lesson to as to why the impeller should be changed every year or two. Changeout also assures all the bolts that secure Lower Unit get removed/cleaned and resealed or re-antiseized before they are too far gone. Just as importantly

this annual/biannual changeout prevents the Driveshaft from seizing to Crankshaft.
I did try removing these 2 seized impellers with a brief (couple hours) lubricant soak and Visegrips. This didn't work. It was only after soaking a couple days and then using the heat gun did i have success. I hope this helps...