Yeah, you might need Emmert Anatomy 101 open for this...
Now said Taper Adjustment Knob is held captive in the front vice jaw by a... well, I dunno what the technical term for it should be, but I assumed some sort of spring clip thingy. It looked like this:
So a knocked some of the paint off and had a pull with a pair of needle-nosed pliers. Strangely... soft. Hmm. Oh well, when in ignorance, get out a hammer. Okay, a mallet. And a screwdriver - of course - and apply a little persuasion to the item in question.
Somewhat to my surprise, there was no springiness involved at all. Instead a lead washer had been broken in two and the two halves forced into the slot in the casting, and thus round the shaft of the Tilt Adjustment Knob. That explained the softness at any rate.
Now I'm no engineer - you've probably noticed - but surely this is not the original design? I can't believe there's not a less - how can I put this? A slightly less bodged solution to the problem? My comments box is open.
Failing that, I may have a slightly smarter lead washer in the Box of Bits I suppose...