Fuel pre heater 96 W210

[Lowflyingbird]

Hi,
I see some diesel residue around the fuel pre heater, I plan on buying a new plasic line to go from the heater to the strainer (looks old). I can see air in the lines. All the other lines seem to have been changed prior to buying the car. I also see the same mild wetness on the IP. I will purchase copper crush washers and O-rings for the delivery valves, it couldn't hurt to put in new, the car has 220 kmi on it. I already have the socket from my last 99 W210. My question is, is there any gasket or other O-ring possibly needed for the diesel pre heater? Where is the best place to get everything from one source.
Thanks
Lowflyingbird

[KarTek]

There is a gasket under the fuel heater:

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