I've read everything here about injector nozzle replacement.

[Clemson88]

I've read up on precombustion chambers too. Why in the world would one pull the PCs and what would one do if he needed a replacement? I'd like to have some direction on that question if some of you experienced folks would care to educate me on the subject.

84 300SD, of course.

[bentrod]

For the most part the only reason to pull them is if your decking the head.
Why would you need to replace one outside of some sort of heavy metal damage/ engine parts colliding.
At one time I did some experiments on a 1977 300D. I had some extra PC's to play with.
I pulled and modified the PC, drove out the mixing pin, then did it again and cut off the bottom of the PC. I was trying to make a home made direct injection version.
The injectors and pistons are just not compatible with this type of back yard engineering.
All for nought, both ways it ran worse and more worse, LOL.

[mach4]

A common reason to pull them would be if they were leaking and it was necessary to replace the seals. Other reasons would be if the engine started running poorly or started making noise (indicating a possible damaged or burned out ball). Or, to get a borescope into the cylinder to check the bore or pistons.