If the spring is stiff enough to have much effect on a wobbling shaft, wouldn't pushing it to one side of the bushing cause even more wear? Eventually would the rotor start hitting the inside of the cap? Now that I think of it, I doubt I ever knew how much clearance was between the tip of the rotor and the tip of the cap.
As Dynasoar pointed out, any grease caps I've ever worked with didn't have the spring and disc, and you had to turn the cap so often in order to make sure grease was pushed into the bore.
Interesting item here. I'll have to read and learn more.
