Thanks all. That’s rather wonderful. Half nine isn’t the best time to go hammer and tongs at something like this, but with some very sparing filing on the sides the bearing slid nicely between the ‘horns’, and with a minimum of filing with a number 4 on the sides of the channel in the back plate it moves freely up and down but without a chance of moving side-to-side.
So that seems like job done for the tutorial team. I admit to a profound dislike of two-component glue (partly because mixing it seems to be so wasteful) so the next step I have to do, following the instructions, will have a different risk of stickiness…
First I will look at putting some solder in the corners. What’s the expected travel of the bearing up the hornblock? Half way?
Sorry, that looks like more questions!