Yup theres a torq bolt on the end of the sprocket.
I tried to slacken this but ended up turning the whole bottom end and got scared.
According to ELSAWIN this is how you change the pump but I bottled it.
 
Hmm, is it really worth it as the pump looks clean from where the strainer is mounted, filter bracket is next off, i read on vag cat there self locking.