Volvo VNL 780 Front Air ride problem

Good morning everyone
I just got myself very nice 07 780 with D12 engine and 13 speed from first owner....
I purchased this truck for such a low price that I didn’t even test drive it ... Engine starts, no leaks, looks good... it’s mine...
So i start fixing small things (regular maintenance), oils, shocks, brakes etc etc... Ride is little hard and weird... front suspension act really weird, so i look at the gauges and front suspension have only 5 psi off pressure. I think that’s way too low... it looks like there’s sone air in air bags but not enough at least for me. Truck have separate valves for each side and they are at the same height... any ideas what could be the problem??

 

I will try to adjust ride height then. Thank you

 

Previous owner is no longer in US.....

 

I don’t have vibration, it’s just weird feeling of front axle, kind of hard and unstable... I remember on the 09 Volvo 730 that my front suspension had around 50-55 psi off pressure if i’m correct...
I will try to find some good info how to check front air ride...