I have a John Deere 3039R tractor with a loader with a clam shell bucket. The bucket stopped opening and it went back to dealer under warrantee. Worked for a year then inoperable again. Dealer came to property and service person replaced quick connect coupling near bucket. Said the coupling wasn't allowing hydraulic fluid to pass through. Left defective male fitting he replaced. Worked a week and again not opening. Can anyone help me with instructions to test the hydraulics from the Rear Outlet Selective Control Valve (SCV) to the clam shell? There is power to the relay box which clicks when up and down buttons are pushed and to both magnetic units on the CTV. Also, clam shell is in the solid closed position. Is problem in the CTV or is there one or more defective quick release couplings. All have been checked from the CTV to the clam shell and look good.