i think he is referring to locking the quill in the quill housing casting .. not ( yet ) failure for the morse taper to lock up .
but hard to believe there are 3 loose quill/housings in the whole world ... ?? and either the whole length of the quill or the surface just around the clamp ..... does the quill rattle at the forward bore of the quill casting ??? if not maybe change the location of the clamp to the right .
try turning an eze-cut / aluminum ... false quill .... and use it as a test tool/gauge see if quill ... or bore ... or your clamp screw is wrong ..... bottoming ??
i like a mystery .