My sewing desk chair was not rolling like it used to. It was difficult to move back from the desk. Since I am in a major clean, rearrange, and remodel of my sewing area, I decided to check it out. After turning the chair over I was amazed at the amount of thread, pet hair, people hair (DGDs like to play hair salon!) that was wrapped around the wheels. I spent over an hour cleaning it all out. I recommend everyone check theirs periodically. The chair works great now. I ended up using scissors, an old seam ripper, needle nose pliers, and bent nose pliers. I had the chair for over 5 years and never thought to clean the wheel area.
Hope this helps someone else.