AZV motor pump nozzle sealing

Hello everyone.
My problem concerns a Volkswagen Touran.
Motor AZV

Unfortunately, I couldn't find anything using the search function.

The engine starts very poorly when it's warm, it misfires significantly, but it always eventually starts.

I wanted to replace the seals on the injector pumps.

The nozzles have two clearly visible O-rings of the same size.
There's still a small O-ring included in the set.
Where is he going?
Does the nozzle need to be unscrewed for that?

The nozzle does not have a seal at the bottom because it is conical.

I would appreciate it if someone could help me here.

Best regards, Mario.

It goes in the upper part of the PD (presumably a piece of equipment), it's the O-ring of the piston pin, which you can see above the spring.