Hydraulics randomly won't work on komatsu pc 200lc7 excavator.

I have had the komatsu dealer out twice,replaced lock solenoid have power to it. Replaced self reducing pressure valve.Have had pumps tested and are around 3300. Help this is going on two weeks and a lot of money down the drain.

Hydraulics randomly won't work on komatsu pc 200lc7 excavator.