Fasthitch won't hold position

It was suggested that the check valve spring might be broken, but I disassembled it today and found it is a one way check valve, and that the spring looked fine as well as the rest of the insides (valve, seat, ball, etc.). I plan to replace the Orings in it but don"t know if that alone could be the problem.

Has anyone encountered this problem, and what did you find the problem to be? Thanks alot.

If the linkage is intact then your problem must be internal in the control valve. The control valve while it looks like other remote control valves, internally it has a set of spider gears much like a differential. On one side of that valve there is a lever connected to linkage I mentioned in first paragraph. On the other side the control valve lever. Those spider gears connect the two sides and if damaged or broken will have the same effect as external linkage unhooked.

If those spider gears are broken, I'm not sure you can still by new ones. My 560 had those go in mid 1970s and they were quite pricy back then. I replaced my valve with a complete regular valve from a 300. Of course I lost the draft control feature. If you don't mind loosing the draft control any remote control valve from a 300, 400, 330, 350, 450, 340, 460 or 560 will fit and operate hitch.