I was recently using my SuperGrind 2003 which has been upgraded to use the stainless steel shaft with an EzyLock nut. The nut was well locked in place, holding the SG-250 quite tightly, and it took extra tools to remove the nut.
As I dove into the screw threads to figure out how the nut got stuck, I found it was rather full of some gunk. It was easy enough to clean up, but it does bring me to a thought about a best practice.
I already lower the water trough, but going forward I will also be sure the nut is removed or at least loosened.
I bought a T7 second hand (actually the wife picked it up at an auction for me) and the wheel was rusted solid on the stainless shaft. The wheel broke coming off. The shaft was also well worn. It looked like it had never been lubricated. In hindsight I could have taken it off with the correct technique but hindsight is marvellous.
I always remove the wheel after a sharpening session and have storage for all of the wheels to allow them to dry properly. I also keep the shaft well lubricated.