Scat Trak 15003 boom malfuctioning

[johnk]

Working on a Scat Trak model # 15003 serial # 101233. The only boom function when running is up. Down, curl up and curl down feels locked out electronically ? or hydraulically ?. With engine off and key on boom can be lowered. It drives ok but was low on fluid and was topped off with new oil. I am a diesel mechanic retired and working on this for a friend and I am baffled so any help would be greatly appreciated. Thanks.