Slight knock on OM606 turbo?

[Parrot of Doom]

I took the fuel filter off today, filled it with Redex injector cleaner which contains cleaning additives and a cetane booster.

Filled it to the brim, put the filter back on, and started her up. Everything runs fine, took it up the road and went for a spin, opened the engine right up and everything was sweet.

You can watch a mobile phone video of my engine here using quicktime

However there remains a nagging little bit of knocking that I can't seem to eliminate. You can only just hear it, its very faint, but if I put my finger on the 2 lines from the injector pump to the injectors of cylinders 1 and 2, I can feel the knock on one of them (the lower line of the two).

I wonder if somebody could do me a favour and see if they can feel a similar knock by putting their finger on each injector line?

I'm wondering if its worth buying the injector removal tool, pulling each injector out, and cleaning them out? What is the price of a new nozzle for these injectors (the MB system suggests you can buy all of these as service items)?


/edit: youtube version of video: http://www.youtube.com/watch?v=-9FLGsp7rdQ