Loader strange hydraulics

[nogo]

Hi to all,I just bought a 1975 255 massey and it seems in good shape.One thing that dosen't seem right is when I use the loader.When I try and raise or lower or tilt the bucket the levers seem to be forced back to the neutral position.When that happens the levers become hard to operate and hydraulic action slows down.The levers have been welded before I bought the tractor so it has been a problem before.I have looked around but haven't been able to locate this problem in detail.I am a mechanic by trade but not familiar with hydraulics.Thanks

 

[nogo]

Will post in hydraulics thread