Komatsu PC200-7 difficult to turn left right after 1-2 Hours of operation

Hi Guys,

this is my first post, i have been reading this forum for years.
really help to solve most of my issues with my excavator problems.
and this time i decided to post because i havent found any solution for my problem in this forum and anywhere else.

i Own excavator hire company, most my units are 20 Ton class excavator

I have had this ongoing problem with some of my Komatsu PC200-7, me and my mechanics have been trying to find the cause of the problem for awhile (a year or so), with no luck.

the problem is, after 1-2 hours of operation or after the engine is warm, the hydraulic is warm. it is very difficult for the excavator to turn left/right, but going forward and backward (with both track operate) are ok.
the swing, boom, arm and bucket movements are normal.

i changed the swivel joint seals, checked the motor travel parts inside, and even overhaul the main pumps. the problem still there :mad:

your advice, input and feedback are appreciated :)

thanks

Komatsu PC200-7 difficult to turn left right after 1-2 Hours of operation