That's not much info but there are several things that could cause this. Can you post a pic or 2 showing the valves and knobs under the seat and back on the rock shaft?
Don't have a solution but do have questions. Flex line coming out of the control valve looks like it goes to a leveling cylinder on the lift arm. Would I be correct that the loose end of the flex line that is going into the transmission was once hooked to the other opening on the control valve? If so, where is the control valve to that leveling cylinder. You definitely have something optional here.
Grainger, I don't see a loader. Does it have a loader? Sure agree a little history would help.
still not alot to go on, did they ever work for you ? AS stated it very well could be an adjustment to one of the exterior valves near the r\s rear of tractor,does the loader function in all positions ? If so try holding the lift lever on the loader and move the 3pt lever to see if it reacts,report back-where is the middle round knob positioned thats under the middle of the seat ?