770 Hydraulic Issues

I recently outfitted my 770 with a snowplow in preparation for this coming winter. I can lift and lower the plow successfully, but as soon as I take my hand off the lever, the plow drops fairly quickly. From full height, it probably takes 3-5 seconds to reach the ground. This occurs when using the right side hydraulics. When I switch to using the left side hydraulics, the plow maintains its height.

I assuming there is an issue with the right side hydraulic valve assembly. Is this something that can adjusted, outfitted with new springs and gaskets, or does one typically need to purchase a new assembly?

The tractor is a '65 770 with a power traction hitch. I installed a selector switch for the right side hydraulics so I can switch between controlling the hitch and controlling another device (in this case it's the height of the snowplow). The left side hydraulics are normally hooked up to the plow to adjust the angle.

It's readily apparent that the right side hydraulics have been used significantly more than the left side. The left side lever is steady in its neutral position and there is firm resistance when operating it. The right side lever is wobbly with less resistance when operating.

This is a relatively new tractor to me and I haven't used the right side hydraulics much previously, so I can't say whether this issue just occurred or has been present for a while. I recently rebuilt the hydraulic pump, but didn't touch the valves.

Does the hitch maintain ITS height when you are using it?

And if you switch the hoses around so the valve works in the
other direction, does it hold then?

Most likely the problem is in the valve. The valves have a built in thermo relief valve as well as a load check. Do you have a book? Also my email is open.