DF60 2002 PTT Pump Manifold Assy

[stroba]

Hi all,

I have a Suzuki DF60 -02 and I´m having a problem with the PTT pump manifold assy. Last summer the manual release valve broke and all the PTT fluid leaked out. I changed the valve and everything was ok. This summer the screw underneath the manual release valve broke and all the fluid leaked out again.
What kind of screw or valve is this? Does it do anything or can I seal the hole? Can I order only the screw from somewhere? When I checked here:
2002 DF60 Suzuki Marine Outboard POWER UNIT (MODEL:01-09) Diagram and Parts
I couldn´t see the screw... Is ordering the whole assy the only solution?