Ford Focus 1.6 Tdci 13 plate

[BigNorm]

I have a Ford Focus Titanium 1.6 Tdci 13 plate. It went in to limp mode. Looking at the problems others had, they say it's possibly the fuel filter. I have changed the cartridge, primed the filter but it's still struggling to start. I have noticed on the black top fuel filter cover where the fuel lines & electrics connect to, has fluid under the transparent skin on the underside  of the top filter housing. Is this normal? 

I have ran my obd scanner on it but it's not finding any errors.

Any help is much appreciated.

Edited August 16, 2018 by BigNorm
Missing wording

[drsdriver]

You need a hand held fuel primer when you change the fuel filter. It’s a real pig to start otherwise.