Which don't involve replacing the whole screen. On one side of my screen, the bit of metal the wiring hooks on to has fatigued and snapped off. Any ideas on easy / safe way to rejoin this connection between the metal of the demister element and the wiring loom?

use a spade connector and solder it on?

I have a vague memory it snapped in an awkward place to reach with a soldering iron, but a very sensible suggestion there.

Stick it on and then paint over the join with some conductive element repair paint.