3-Point Hitch John deere 4300 3 point hitch arm problem

[Matthewd43]

I am new to this site but I have a Jed 4300 with a backhoe the leveling arms where stuck in the up position so I took the seat off clean screen also the adjuster valve and valve under seat for flow rate it was working fine till I heard a loud bang arms went down and now there is now pressure any takers for this problem .?:confused2:

 

[Matthewd43]

Old Jed was a millionaire correction on previous post it is a John deere 4300