Bing187, the OP, joined in 2010 yet has only posted 41 times since and has not yet come back with any more info since starting this thread.
I'm hoping he returns and gives us more information regarding the several issues he has had and status/resolution of his most recent issue.
I do find it extremely unusual that he has replaced hydraulic cylinders three times, a loader valve and yet again is having hydraulic issues. There must be some common thread to these five issues in a system which is highly reliable, particularly with only 310 hrs on the tractor.
It would be a service to the TBN community to let us know additional details and how the recent issue is resolved. I understand the OP is frustrated.