Have an early model 765 that the 3 pt arms won't lower with the switch in the cab, switch on the fender, or the controller on the side of the arm rest.  Here's what I know:

It will lower just fine with the relief valve.  Raise fine if lowered with the relief valve.  Will raise to the stop limit if set.  
I can lower it with the skid steer bucket on the arms but it moves about 1% every 3-5 seconds.  
Have tried new switch, ecm, solenoid.  Getting full voltage back to the solenoid.  
Took block apart but didn't see anything that looked out of place and of course reassembled it and same results.  
3 pt position sensor is working correctly.  Raise and lower limits set at 100% and have tried other settings. 
Power to the solenoid moves the 'plunger' in the valve body. 
Remotes are all working as they should be (even after disassembling).  

Dealer thinks block needs rebuilt and they could absolutely be right but i just have this feeling i'm missing something but not sure what.  

Any ideas on what might be up here?  

Thanks!