David, I have been wrong in the past and I may be wrong this time, but, I think the spring fits over the spigot on the threaded bolt/plug and the ball goes into the bore to form a non return/regulating valve. As bolt has a sealing washer it's a fixed setting. Reassemble it, bleed it and try it but not on the car !. If the jack lifts just try standing on it/get someone else to stand on it before you lift any thing you are working on.
Your safety must be your first priority.
I envy your fitness at 70+, I'm wrecked at 61 but still work on the car and van then suffer the back/shoulder/ everything ache afterwards!!
Nathan.