Thanks for that
Wait - maybe the long axles with the discs on the end are different and off-center. You can only make it work one way, anyway.
Legs removed with relative ease - thank you for the excellent description.
The long axles have three flat sides (two with plastic clips on them) and one rounded side. It is that which determines which side of the keyboard they go on. One side has the rounded edge facing the front of the keyboard, the other side the rounded side faces the rear. And yes, once you pull them apart it is MUCH easier to see how they fit together.
Once I realised that I wasn't going to break it, I pushed with one thumb while holding the other hand outside the case in case something flew off (I do have fairly strong fingers).
The first spring I tried to remove before fully removing the axle, and it did its spring thing and ended up half way across the room.
The second one I removed the axle first, then just lifted the leg and spring out together - much easier.
Also the heat much have been affecting me more than I realised when I sorted the keycaps out, and I had half one piece and half two piece. That is rationalised now, with nearly all the keycaps being 2 piece.