I assume you have the pipe screwed out of valve which you must. But, I just cannot walk you through the procedure I use but will try. I clamp the nut in a vise, put a pipe wrench on the pipe to loosen it. Then put other end of spool in vise. Unscrew large nut. Take the screwdriver slotted adjustment screw out, take spring out, pull inner sleeve out, catching all balls that fall out. Pull pipe off, put adjustment screw back in full thread, put a vise grip on end where screw is . It won't hurt it as screw supports it from collapsing and not a surface you need to worry about. screw out the actuator. Inspect all parts for grooves and wear. Note position of centering spring washers and cup. And from here, you could have two different styles of detent mechanism. Early models had piston with o-ring on it . Later ones had o-ring , backup washer and small retainer pressed in end of detent. Anyway, you need to replace O-rings. Then you assemble actuator to spool with centering spring and cup in place. To reassemble balls I pack balls in place with grease, slip pipe on, then ball and seat. Insert grooved detent sleeve. Install spring and screw. You have to make sure it stays in the centered position. Put the big nut on, hold it in vise and tighten pipe securely. This assured you it will come out of valve next time you take it apart. When you install the spool in valve, you need to put spool into valve , then reach around front and pull through so you don't mess up the detent, tighten large nut but not much. Hey, I know I have missed a few opertions here. Come on over, I will show you how. By the way, after you have spool separated from all mechanism, take out front o-ring and see if spool will slide through the valve easily. Must be someone around your area experienced in them as it is a common repair. Good luck.