Our flush toilets are equipped with that flush mechanism that replaces the old type with the arm and ball ( don't recall the brand name,but I'm sure you know the type.)
One of the toilets tanks would not refill after flushing yesterday. I looked and found the "float" for lack of the correct name,but it's the piece that rides up and down on the vertical arm when the toilet is flushed and opens and closes the valve when the tank is refilled was struck in the closed position not allowing the tank to refill.
I remembered that "WD" stood for Water Displacement and figured that maybe it was worth a try to spray it on the arm to see if it would free up the float.
It worked as advertised and the toilet is working properly again.