1980 komatsu pc 120-3 excavator slow swing an bucket

previous owner stripped all wires on machine boom works up an down but swing an bucket crawl unless I'm working boom up and down then they seem to operate with in reason yesterday swing stalled completely I pulled a solenoid valve off the main hydraulic pump and put power to it to see if was working it was so why did previous owner cut the wires to it ? while it was off tried moving piston that plunger hits from solenoid don't think it moved but I did hear burping in hyd tank put it back...

1980 komatsu pc 120-3 excavator slow swing an bucket

1980 komatsu pc 120-3 excavator slow swing an bucket