9N 3-Point Linkage

If so, this is not unusual, it often seems to happen when running an implement that transmits a lot of shock back though the linkage, like a backblade on rocky ground.

There's nothing holds it on but the spring tension of the two ends of the control linkage. You could try increasing that by bending them together, but I wouldn't do that if it were mine. What I've done in the past is take a turn of soft steel wire, like mechanics wire, around the ends of the linkage to hold them together. It's kind of tight working conditions but not impossible to do, especially if the drain plug is removed. You could also pull the valve itself - it just slides out backwards when it's unhooked from the linkage - and inspect the two ends of the T-piece. If rounded or worn, you could freshen them up to help them engage securely in the bushings on the ends of the control linkage.

HTH

llater,

llamas