Bobcat 331 boom lift function

[RBtom]

I have a 1999 bobcat 331 mini excavator.
Boom lift function.
Seems like something bypassing in that function. Drifts so bad the machine isn't operable.
Will not pick up any weight and just falls to the ground. Strange part is that it seems to be the only function affected. This actually started a couple years ago but it's got progressively worse.

Thanks for any help.

 

[RBtom]

I have adjusted every valve affecting the boom lift with no success.