Step 13: Check valves and safety overload valve
Second photo--Install the parts in the order shown in this photo from step 8. (The release valve and the plunger are not shown in this photo.) Use the new balls from the parts kit. Do all of this inside a pan or shallow cardboard box so none of the balls are lost if one gets away from you. Tamp the parts down with a small screwdriver so they settle down as far as possible in their hole. Carefully start the screw plug with a screwdriver. It is easy to crossthread. Use the special screwdriver made from a hardened bolt to tighten the screw plug with a wrench.
Third photo--Install the parts shown in this photo from step 8. Drop the new ball into the hole. Insert the spring into the open end of the cap and drop both into the hole. Insert the screw plug. Carefully turn the screw plug until the valve assembly bottoms out. Back it off 1 3/4 turns.
I chose not to install the metal plugs that close the valve holes yet in case I would need to open one of the valves during testing of the jack to correct a problem.