Having recently emptied the OXO pepper grinder we (mistakenly?) bought as a salt mill, I took it apart for a deep rinsing and cleanup:
It turns out the somewhat corroded square shaft is aluminum, neither the cheap steel I expected nor the stainless steel it should be. Perhaps OXO cost-reduced the shaft, discovered aluminum is a poor choice in a saline environment, and changed the packaging to compensate?
Removing / installing the Jesus clip requires careful whacking with a hollow-tip punch against the shaft, with the whole affair laid flat on shop towels, the handle held down to prevent rotation, and the wrap-around body capturing the escaping clip.
Shaft corrosion as of Summer 2020:
Soaking the body in hot water got rid of salt crusts and filled the shell with water. There being no way to completely dry the thing, I parked it in the sun for a day, refilled it, and was unsurprised when the (dried) salt turned into an assortment of moist crystals.
We obviously need a real salt mill …
The Smell of Molten Projects in the Morning 
Our next-to-last pepper grinder came with a salt grinder. I’m supposed to stay away from salt, and Julie doesn’t use it, so there’s a barely used one sitting idle. Price is right, too. [grin]
Give me an email.
Pete
I tend to grip small c clips on the flats with good quality needle nose pliers opposite the open side and just yank them out
For e clips I sometimes use a tiny screwdriver to pry on hollow spaces.
Never tried to whack one off, it doesn’t sound like fun
Working inside the mill put a definite crimp in my style; I have no idea how to dismantle the knob to take it further apart. The square shaft hid the parts of the clip I’d normally abuse, leaving only the little tips of the ends free for hammering.
Sometimes I should say “Don’t do it like this!” and proceed to be a Bad Example™.
Dismantling is usually easy, just apply your Grand marteau (TM)
Subsequent reassembly, however, tends to be a different story :)
I have a bench drill press that required the quill to come out, but with no obvious way to remove the pinion which must come out first. After oiling, trying to lhs unscrew it (with and without impact gun), applying heat, bearing puller and custom puller adapters I finally resigned to remake the pinion and shaft it’s mounted on. I then proceeded to chop the thing off with a bandsaw and finally freed the quill, but believe it or not I still have no idea how the damned thing was supposed to come off. It looks like it was grown or additively manufactured in situ which would be quite a feat today, let alone 50+ years ago when this thing was made
Not deploying the angle grinder must count for something!
Must have been one of those shrink-fit assemblies requiring both a torch and dry ice …