Almost right

"There's a hole in my y-board, dear reader, dear reader,
there's a hole in my y-board, dear reader, a hole."

Now reassembled - but it still doesn't work - the pivoting arm hits the PTFE slider where I've drawn it. Luckily, I haven't got around to glueing it yet.

So here is the amended y-stage diagram:
They need to be right up in the corners (or cut them shorter).