5303 rockshaft will not raise

[Oletrapper]

I'm not new to TractorByNet but haven't been here for awhile.
I have a 2006 JD 5303 and the rockshaft arms will not raise. I am thinking something is wrong with the rockshaft control valve. Has anyone had a similar problem? Thanks in advance for any help anyone might provide. OT

 

[Tx Jim]

How long since hyd filter was changed & trans oil screen cleaned?

https://partscatalog.deere.com/jdrc/sidebyside/equipment/74433/referrer/navigation/pgId/552370930

 

[cooksmtn]

I'm not new to TractorByNet but haven't been here for awhile.
I have a 2006 JD 5303 and the rockshaft arms will not raise. I am thinking something is wrong with the rockshaft control valve. Has anyone had a similar problem? Thanks in advance for any help anyone might provide. OT

Had the same problem recently with my Mitsubishi 2050. Happened unexpectedly at the far corner of the property while working the rear blade hard. Had to ratchet strap the blade up to get back to the shop. Wasn't looking forward to the repair, expecting major mechanical issues, since the hydraulic oil and filter had been serviced recently.
Had to remove the rops and fenders to be able to remove the top of the case, to which the control valve is mounted. Inside showed no mechanical issues (400 hrs), but I removed and disassembled the cylinder that operates the lift, no issues. At that point I figured it had to be in the valve, but I wasn't inclined to remove and disassemble it. Flushed it well, and reassembled. Everything worked fine once the air bled out.
I figure a tiny bit of dirt got into a check valve in the valve body, keeping the cylinder from developing pressure.
Hope yours is just as easy. I did have the advantage of a good parts diagram and service manual.