Ah! So it is the spindle after all. So the Rodney mill is actually pulling the lathe spindle -and locking it whereas the 'normal' running without the Rodney fitted or working is 'flopping about' nipping and freeing ad finitum.
So you might have to strip the whole lot down- and perhaps blue and scrape the front bearing- before putting it all back----- correctly.
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Well, Charles- my apologies- I was wrong.
Meantime, my kind regards
Norman