The spool inside the priority valve will stick at times. Not to bad a job to pull the plug on the bottom of the valve and drop the spool out so it can be cleaned and polished up. Just be sure not to round the edges over on the spool. I usually chuck them in a lathe and use 1200 or finer sand paper under a flat file to go over the spool. Probably could do the same in a drill press if no access to a lathe. There is also a steering pressure relieve valve in that priority valve and they can go bad. Last one I worked on you could adjust the pressure but it would not stay where you set it. I assumed the seat was bad, it was still available from CaseIH. The system is pretty easy to trouble shoot if you have some gauges. Just tight quarters and you do tend to oil up your shoulder joints.