Hi friends !

During a visual inspection for the manifold was found , that the Orifice 0.38 mm was installed under SVL valve instead of it's original location - under PCL ( Pressure Compensator Valve ).
I had put ORF3 back to PCL valve and the function Lift / Lower on the truck is working perfect now.

Many thanks for your help and support !

I disassembled the pressure control valve from main hydraulic cylinder - every thing is fine overthere. The valve is clear and no any debrises or dirt inside cyliner.
For now I have to remove the manifold from the truck and do a visual inspection for mentioned above valves one more time.

Performance settings both of lift / lover - 9.

Thanks ALL for replies !

Lovering valves as per hydraulics diagram are SPL ( proportional valve ) , SVL ( normal electrical valve ) and PCL ( pressure compensated valve or hydraulic latch as I correct thinking ).
Both of them I removed from manifold and checked physically and also by 24 and 36 VDC correspondently on the lab bench - they are OK.
Using Analizer I checked lift / lower POT4 : 0.6V - 4.1V - 7.7V , it also good.
I did a C4 calibration for lifting / lower - the system accepted that calibration.
Today I'm going to remove the pressure control valve from main hydraulic cylinder to see , if it contaminanted or not.
The truck was fully operational after I did repair but after a few days this issue with so slow lowering happened.

Thank you once again.

I know that the lowering valves will cause a slow lower on the SC5200s. Not sure if the SC6000s have them as well. If so it might be worth checking. If not, disregard.

Have you tried recalibrating the lowering valve? Go to settings, calibration, 2.1 (if I'm remembering correctly). Then then Lift will automatically set the lowering speed to the proper speed.
Otherwise it may have been set in the performance settings as you can change the speed of lifting and lowering in the performance settings.