Komatsu pc 400 LC-8 stick cyl drift

hi we have a komatsu pc 400 lc-8 with very bad stick/arm cyl drift also seems to have low power in the stick function as well, I have checked the main pressure at the pump and it is 5500 psi , anything easy to check swap something with other side of circuit ? I have no manuals for komatsu equipment . Any help would be great thanks .

Komatsu pc 400 LC-8 stick cyl drift