An update.
I dropped the sump pan, and the pick up was clean. The pan itself was also clean. So the sludge seems to have been localised to the top of the engine, which would make me think it was the beginning of the sludge being created by the faulty injector. Managed to snap a bolt from the sump, only one, so fuck my life and Toyota bolts. All of them are tight, I’ve not torqued them, because I can live with one bolt broken but two or three? Nah mate.
I got the new stretch bolts and fuel return screws, which have a 12mm head instead of 17mm. I’m not going to lie, I took a can of compressed air and carb cleaner and the area was all spotless. I put the bolts in finger tight then took my new Halfrauds torque wrench to it. By the 3rd bolt I think I was having the beginning of a panic attack - not exaggerating- but the bolts got tightened to 22Nm, screws to 16nm and 12.5nm.
Had a look at the rocker cover, and the chamber where the breather goes in to was full of muck - a considerable amount. So took it all apart and spent a lot of time agitating it with petrol and carb cleaner and a brush. All good, bit of RTV on it (as it had some anyway) and it’s on the engine now.
Fuel pipes were fitted, in my haste to take them off I removed the fuel in line which was a pig to do. Ended up removing it altogether and refitting it as otherwise the line wouldn’t fit on to the rail. All lines tightened on the rail and on the injectors, everything bolted down… I misplaced the clamp holding the lines to the EGR. It was cracked anyway, but I need to get one now.
So yeah, a better day, but still going to be waiting on some bits before it progresses.
I’m assuming I can program injectors and do fuel pressure tests without the engine running?