ASV 4810 loader trouble

[Bison]

Hi there,newby here(to the site)
I got a ? for 4810 owners.

my loader displays a 8-10 drop after releasing the joystick,but hold after that.Position of the loaders arms don't matter.
The lift cylinder seals are verified good .
must be the control valve having issues,but what?

Happens only when hot,no drop when cold.
Dealer knows dick all.

Thanks