New Holland TC18 3 point Issues

[Jake985]

I have a New Holland TC18, the 3 point raises its own weight but standing on it is enough to make it go back down. Loader hydraulics and power steering work well. Hydraulic fluid is good in level and condition, new spin on hydraulic filter 3 hours ago. I tried turning the slotted head valve spool on the hydraulic pump but it made no difference. Not really sure where to look next, if anyone has any advice I would greatly appreciate it.