Look at this thread .
http://www.tractorbynet.com/forums/new-holland-owning-operating/282549-power-beyond-backhoe.html
Post # 2 is my reply with pictures were I believe you are talking about . Based upon your info above , I am assuming you have never had the backhoe off . Is the 2nd hose from the Backhoe attached under the seat ??
The rear connection is the return and is left unconnected to any thing . That Front connection Will connect to that covered stub . Otherwise no power / lift on the 3 point . ( Assuming it is like my set up , when connected to B.H. , the 3 point is disabled ) .
Warning : If You never have took it off , The Main thing to Remember is , Never Disconnect either of the 2 hoses from the B.H. with the tractor running . This will likely blow out the pump if you do .
My Procedure for removing is this :
1) Position tractor were B.H. is to be placed
2) Loosen and remove top link , ( Assuming it is being used )
3) Remove the 2 pins that are located at the front of the subframe , basically below / slightly forward of your feet , 1 pin on each side .
4) Lower Stabilizers to slightly lift backhoe in the rear bracket that is below the rear pto shaft , ( Again , Assuming that the B.H. had a subframe mount on tractor )
5) Using Dipper and bucket , Extend boom slightly , then lower dipper till bucket contacts ground then watch forward has you apply pressure . As you push down on ground , the forward frame of the B.H. were you removed the pin's , will lower towards ground . Needs to be within 4" to 6" of ground at most , for tractor to clear when driving off .
6) Slightly move tractor forward a few inch's making sure to watch hoses do not get tight . If B.H. appears to be still attached , you may need to adjust either the stabilizers or dipper to take the weight off the tractor and more onto the B.H.
7) If tractor moves and B.H. does not , move forward roughly 6" , Shut tractor OFF . Disconnect rear hose . Disconnect Front hose by loader , then connect the coupler that you removed the B.H. hose from to the very connection that I Believe you referred to , ( See my above link and reply in that other thread with pictures ) .
8) AFTER the hoses are disconnected for B.H. and the before mentioned hose is connected to that coupler , Then start tractor and slowly pull off B.H. . Now you can place blocks under the rear of B.H. and release pressure on the Dipper and Stabilizers .
Although it sounds Daunting , It really is not . Been doing it for 7 years on my tc30 with a 757C B.H. , Takes about 5 minutes to disconnect or reconnect it .
Attaching is reverse , with 2 things to remember . Tractor off when connecting hoses and I put very little pressure on the dipper , boom when hooking up the top link . Basically it is only slightly tighter than hand tight .
Read the above thread , study the pictures , I may be talking about a whole different set up ??
Fred H.