The L35 has a directional hydraulic valve lever hehind and below the right side of the seat. When the valve lever is pushed in, the flow operates the backhoe unit and when it is pulled out it operates the three point hitch. Have you tried this valve in both positions?
I'm thinking one set of hydraulics is taken up by the front loader and the other set is split and controlled by the directional valve so you can either raise the three point hitch or operate an implement. Once you set the level of the three point hitch, you may have to switch the flow back to operate the implement.
I just bought my L35 and I'm new to this so I'm likely not much help. I've never taken the backhoe off. I'm in the process of looking at other implements so I'm real interested in your problem.