kobelco 250 weak left track

hi, have a kobelco 250lc-6e dynamic acera left track is weak until I unplug independent travel solenoids then works fine. any suggestions? have 24 volts at both plugs with key on engine off. is this right? what controls current to these solenoids? when you push left travel you can hear a bypassing sound and you need about 3/4 of lever travel to get track to move while right side is what I would say normal. if I pull the electrical plugs on solenoids both sides act normal. thanks, john

kobelco 250 weak left track