[Tx Jim]

Have you turned rate of drop valve(item 30) under seat 1/2-1 turn CCW? Does 3 pt control handle move forward in quadrant? It's possible cam follower(shaded outlined part) on 3 pt linkage inside of rockshaft housing has slipped out of control linkage or spring has broken become disconnected. How many hrs of use since hyd filter was changed & suction screen checked/cleaned?

 

[Tx Jim]

I suggest to acquire a bore scope & look inside hyd oil filler hole located in rockshaft housing for spring & cam follower(shaded part) in my 2nd photo.

 

[Tx Jim]

Attachment you posted was no help to my understanding your tractors hyd problem. Closed center hyd's such as your tractor has are difficult to diagnose in person & much more difficult looking at a computer screen. What type of hyd diagnosis have you performed? Have you checked GPM of trans pump with hyd hi-lo in both speeds & pto in both on & off positions?