Replacing parts in backhoe valves - 580B

First off, for anyone searching for drawings or part numbers on the 580B backhoe, use the parts.casece website, click find parts by model, search "35 backhoe". Should be the first result.

So to my question, I took the hydraulic valve assembly off the backhoe, what parts would you replace if trying to improve the functionality and pressure from the backhoe hydraulics? My main issue is lack of power, and some movement of cylinders when operating another cylinder. Thanks!...

Replacing parts in backhoe valves - 580B

Replacing parts in backhoe valves - 580B