Diesel leaks, pump help

[lalozf]

Hello guys I have a problem since I bought my 760 84/D24T
The pump leaks some diesel, if I turn the key and the glowplugs work, leaks by the plastic thingy. When I turn off the car continues leaking a little bit. It is not a catastrophic leakage because mileage is 35 miles per gallon, but I want to fix it.

Here you can see this plastic thing and you can see a drop waiting to fall


Here is a general picture of the engine

Do you have any ideas what would be the problem?

Thanks, sorry for my English