WEM Mk4 Copicat - low volume output

[Bushbaby]

Ive just has a thought - how do you ensure the heads are all aligned? I realise now that I did unscrew the shroud to the first (erase) head to see how clean the head was. Is it possible I have pushed it out of alignment with the others (I did try to be as careful as possible when I did undo it)?
Best Regards

Rob