Changing hydraulic for manual head positioning

the manual will tell you to pull the whole thing apart, but if you've got some needle nose you can pick up the seat, and access the cotter pin on the bottom the cylinder. then you can inscrew the top. when you install the new one, do it in the opposite order. when you're screwing the top of the cylinder in, screw it in until the cylinder starts to extend, then unscrew it half a turn, then install the bottom half.