[ttg4l]

Looks like it just needs a circlip to hold the black bar onto the shaft that has the spring on it, with the black bar pushing up against that loose bit of spring that's hanging down.

 

[ttg4l]

That's amazing, thank you! I felt silly asking as I thought this must be something simple, but i had no idea what a circlip was or if I'd need something special. Now I know what to look for. I'll report back if it works!

No worries. Be careful when installing it, circlips are sprung so it might ping off upon installation.

Just had a look on eBay - plenty of kits available with all sorts of sizes, they must have the right size in one of them. Search for "circlips", or "C clips", or "E clips".