I've had this 2011 4320 since 2013 (open station) and only recently needed to use the 3rd SVC. The lever to operate the valve does not move, regardless of the position of the Lock / Unlock lever. It appears that to get under the plastic cover that the operating lever sticks up through to see what the problem is I may have to take the RR tire and fender off...possibly I can remove the seat to gain partial access? Worst case scenario I may have to remove much more stuff in the operator's station platform to investigate the problem just beneath the plastic. The Deere Tractor Repair manual on CD (which I purchased for a 4720) has 27 MB of detailed information; but never addresses my question - how do I get under the plastic to adjust the cables to the valves and to potentially adjust the locking mechanism so that the 3rd SVC lever will move and thus move the spool. From under the tractor the valve body is somewhat above the hydraulic filter; but quite inaccessible so far.