I'm just throwing this out there, maybe it will help someone, maybe not. A number of years ago I lost hydraulic power to the wing control valve stack. The plow and bed worked alright but the wing did nothing. My phone-a-friend hydraulics buddy told me how I could run the wing functions by raising the plow all the way up and going to a hydraulic stall situation (no relief valve apparently). My truck sat most of that summer without wing pressure unable to lift the wing in normal operation. For some reason (probably some free advice) I pulled the supply line from the dump/bed stack going to the wing stack. There sat a pipe plug unscrewed from it's port. Apparently this dumped hydraulic pressure from the system heading for the wing valve stack. I have no idea how a pipe plug would come unscrewed but it did. Simply screwing it back in the port solved the problem. I'll never understand how you could by-pass the system and run the wing with the plow up and the hydraulics screaming. The following photo shows the location of the plug.