Hi all new to this forum and to tractors and have been watching and reading for awhile- but im getting a crash course in internationals in the past 3 weeks- i purchased a 1966 international 434 desiel its a little rough but have slowly been going thru different parts of tractor in hopes of cleaning it up- ive done oil change and filter aswell as drained hydraulics and replaced o rings in both isolator valve and speed flow valve as they were leaking heavily - the tractor has a loader with controls and rear remotes with a single spool valve for rear- hydraulics seem to to be working except for the issue with 3 pt hitch it goes up and down with spool controls but when i release it just goes back in the up position - i have isolator valve open and side lever in forward position as per manual but still does not stop unless i get to desired 3pt hitch position and shut isolator valve then it holds position but just doesnt seem right- if im missing something if theres anyone out there more familiar with 434s it be great to hear from you or any suggestions would be greatly appreciated.