Pictured below is the mandrel I use for pens on those rare occasions when I use a mandrel. It is one of the 'professional' adjustable styles. Lately, when using it, I cannot remove by tapping from behind. In fact, some hard whacking won't budge it. I have to lock the indexer and turn the MT with a wrench to bust loose. Not a happy thing to do to my lathe.
I acquired this thing used and suspect it got spun at some point, or two, or twenty.
Wadda y'all think, should I try to just clean it up with sandpaper or something, or is it toast? I'm leaning towards toast.