Cat 426 Boom wont lift a load unless i start to swing.

Ok so I got a new Tranny in my Backhoe and its been working great so now to tackle the next problem. The main boom is slow to lift and when it has a full bucket it wont lift at all. But i learned this weekend that if I start to swing the boom while lifting it does the job. I can swing left or right, as soon as the stick moves to open the swing valves i get the hyd power to lift the boom. Is the problem in the joystick manifold.any comments is appreciated. Thanks