A couple of other things to check. The marker actuator is inside the frame tube. The op man will tell you how to slide it out to lube the mechanism and it will need lubbed. Also good time to clean out the mouse nest and dirt that is usually in there. Metal line that feeds the marker cylinder lasts longer if tube is clean. If the planter has a separate hose for the marker plug it into the right hand remote on your 4440. If the planter lift and marker are plumbed together still use the right hand valve because it has the 0 back pressure shuttle valve in front of it and will allow the marker to drop. Follow the procedure for bleeding the hydraulic wheel lift cylinders if it does not raise or drop evenly.