Cat 320B Swing Problem

Hi when the hydraulic oil warms up the excavator doesn't swing anymore.
We have tried to replace the solenoid
but now when the solenoid is connected to the power it's not turning anymore
but when we tried disconnecting the solenoid power it is possible to swing the excavator. Also we measured the voltage on the connector it's reading
26.6v isn't it supposed to be 24v?

Cat 320B Swing Problem