Thanks both of you. Yes I was thinking about the penetrating oil, but didn't want to bug the tennant without a solid plan. So, the set screw inside that handle releases a small hub that attaches to the valve stem? How does that hub attach? I see a ridged area for grip, but I see no way the handle won't pull back off. Is that hub just too deep in the handle and that set screw should be hitting the shoulder of the valve stem (towards the wall past the ridged section)?