The starting point for the regulator screw is flush with the housing.

If your fuel system isn't holding pressure that is a big issue that needs addressed. Is the check valve in pointing the right direction and is it functioning properly. If you blow through it it should only allow airflow inone direction and that direction is toward the tank.

Are the fuel lines ok? Is the tank stopper ok?

Which 1.20do you have? I have a lot of manuals in PDF format and could e-mail you a manual if I have it.