On the Remington De Luxe 5:

The variable line space button shaft inside the left hand platen knob looks like this:

See that little thing down there next to the main shaft? That's what I'm calling the mini-shaft. It allows the button to be pushed and turned and held in place, letting you keep the platen in free-rolling mode. This is a replacement left side platen knob I harvested from another Remington De Luxe 5 I bought this week. Replacing the knob could not have been easier. (You just unscrew the knob, holding the right hand knob firmly in your other hand. )My Remington De Luxe 5 is now back to being a fully functioning artist's typewriter.

The original platen knob shaft was, on inspection, slightly bent out of shape, and also and strangely enough, missing the little mini-shaft.

When I put the orignial, now defective, platen knob onto the parts machine, I was able to reproduce the problem I had found on my original machine, after its sojourn in Bexhill.

I know one should not type anything in anger, but I'm still pretty annoyed about this whole ruddy thing.

The Truth about Knobs is out there. Don't let them mess with your mind.