Will be replacing the pipe marked with red - part of the fuel return line (1.9dg Autosleeper trooper)

but from the printout I was kindly given by the chap at he VW garage I'm a bit confused. I've followed the return line from the engine back to the tank and can't see the non-return valve which I was expecting to see (part 20)

Haynes shows a restrictor (part 2) - is this the ceramic bit at the junction marked in the black circle in the photo?

Is the restrictor an alternative for a non return valve? Which is better? Should I just replace the pipe and leave restrictor (ceramic bit) as is, or should I get a non return valve?
Any advice will be appreciated.
Cheers, Andrew