Clicking/tapping when revving 1.9 tdi 105bhp pd

On my 1.9 Tdi 105bhp Golf there is a quite loud tapping noise when revved over idle (no sound on idle). I think it is a problem relating to the cam, the car has covered 100k

I have removed the rocker cover too get a better look and all off the tappets look to be set at the same height....however one looks very flush to the base - Could this be the cause of the noise???

Also 3 injectors look the same, apart from the second one where the springs on it look more compressed compared to the others, is this normal?

Edited 9 July, 20178 yr by dmcc97