Hi I have issue with kobelco 135sr. Boom down and can’t lift track lines first attempt. I checked all check valve for boom system.

Reseal the boom cylinders. When the boom down and can't lift track lines. That time pump pressure is 1300 psi only.But again neutral the joystick and move the boom down position it is moving. I check main pump solonoide, pilot sensors. I removed the boom spool also. BUT I can't found any wrong.