m456 rear shocks question

[Jreyes94]

I've got a set of the m456 yellow rear shocks, I can compress them by hand fairly easy- though they are very tough to retract. They also do not rebound on their own. They do not leak fluids either.
Is this normal for these older style shocks?
Are they blown out, or on their way out?
Also, does anyone know how to adjust these?
I've only dealt with newer style shocks that are a pain to compress and rebound on their own; and have an adjusting screw on one side to change the stiffness.
TIA

[Rasta Monsta]

If they're original, they're Koni units with adjustable rebound. Someone may have put them on full stiffness. . .worth playing around with.