Haven't been in a modern one, but belive they run on the same valve system as older Sheridan and Benjamins. The valve doesn't come out as a unit. Is a complicated arrangement, needing a special tool, and you basically de-gutt it from thge outside. Old onws whent back together with lead crush-washers, so it's not all that easy a reassembly .
I'll have to look for an EB22 diagram to see how the valving changed...been inside several old Benjamins and Sheridans, but not that gun.