the pressure of the tank controlled approx by the motor starting and stopping , is set by the +/- control,one gauge shows tank pressure,gauge nearest wires,othr gauge with valve circled is the line pressure,this is adjustable by the large knob on top,normally have to lift up or push down to change pressure ,don't force it as there are other types of locking used on some machines, you would normally turn line pressure down to paint spray ,,maybe 20-60 psi ,instead of tank pressure of 100psi+
Thanks for that it makes sense sort of.
I just need to work out what I should set the tank pressure at.