Diesel has collected around 3 of my 5 injectors.

I just bought the car so I don’t have any past history on it.
Is it possible the braded return lines have rotted away, or is there a more major problem at hand?

Bet it's the braided lines. Sometimes you can snip a little off and reattach, problem solved.

I replaced the lines 2 meters of hose from MB dealer = 40 dollars