question 8011 Crystal fuel pump leaking

[camelot]

Hello from Canada. Helping our neighbour with their 8011 and you helped so much with a hydraulic issue I thought I'd ask one more question. At the bottom of the fuel pump just under the manual bleeding pump there seems to be diesel dripping from the slotted screw as seen in the picture. Any chance anyone have a diagram of the fuel pump or this area? Also what does this screw do

 

[diyfarmer]

I have a couple of diagrams, can you see the piece you mean?