The marker sequence valve probably needs to be replaced.
It is probably an individual component.
It is possible that it could be rebuilt.
I am not familiar with the set up that you have.
After rereading your post, I wonder if the valve is set up backwards.
Sounds like it is doing what you want it to do, only when it is raised instead of when it is lowered.
Try switching the hoses.
John Deere 750 boxdrill pressure problem
