i just noticed when i unlock the boom and tip it out a bit it does this bouncy back and forth a few times before it holds spongy like seals or the rod nut ?
Perfectly normal for a Case. It works fine everywhere except right before and after the point where it goes over-center, right?
Yep, it has to go over center to get to the lock so just a few thousands of flex in everything looks like a lot of bounce. As mitch sez, perfectly normal. Try putting the bucket on the ground about half curled, stick more or less straight up and down, then use the bucket curl only to lift and lower the boom. If you see the boom cylinder moving in and out much at all then you might have cause to worry.
Everytime i unlock the boom i am amazed how that works inside the cylinder.
In the boom cylinder's piston there is a pressure relief valve limiting sudden big pressures. That may be opening a bit too.
inside? outside or on the control?
Inside the boom cylinder, a hole bored through the piston contains a spring loaded valve. Sudden pressure on the rod side of the piston opens it. Willie