Injectors all came out fine. There isn't anything obvious wrong with nozzles 1-3 (I know that doesn't mean much) but nozzle 4 looks damaged on one side. There's a lot more carbon buildup on that side too:

The sealing washers on 1-3 came out easily too and I found my first issue, I can see the glow plugs sticking into the swirl chamber on 2 & 3, but not on 1! Can they snap off or erode somehow? Will be changing them either way but I wonder where that bit is now

The real issue is that 4th cylinder:

That sideways spray has wrecked the sealing washer and I can't get it out, I'm wondering if it's melted or welded itself to the cylinder head? Has anyone had anything like this before?