Kubota Kx 101-3 2007mod hydraulic issues! (hydraulic control unit??)

Hi!
My Kubota KX101-3@2 2007mod has some issues! It seems like it don't holds the hydraulic pressure in the hydraulic sylinders when I stop using the joysticks!
And it get worse when It gets hot, then it drops faster!
Is it the hydraulic control unit that needs new seals, or what can it be

Thanks guys!

Thomas