I had the same problem with my New Holland 758C on a TC45DA. I was told it goes on and off in a few minutes. I found after it was off that the line to the BH was too short. I could only connect it if it was already in all the slots with the pins in place. Since I could not articulate the hoe without pressure I was having problems. I purchased a line extra long so I could connect pressure lines and line it up with the slots and back into it. When I went to connect it I found that the connectors would not go together. I had too much pressure in the line. I took a 4 x 4 in one hand and the hose with the male nipple in the other hand and drove it into the 4x4. A squirt of oil later it would all connect. The base of the backhoe must be supported on something also or every time you depressurize the line it will re-presurize as the hoe drops down on the stabilizers. Don’t ask me how I know this. Paul