Massey ferguson gc1725m leak.

[Fuller147]

I recently purchased a massey 1725m. Today after mowing for the first time after disengaging the clutch and turning off the pto the tractor made a loud hydraulic whine but when u pulled up on the mmm and 3pt hitch lever it stopped. If you engage the deck the noise goes away. so I parked the tractor. A few minutes later under the tractor was a small puddle of hydraulic fluid. After doing a little searching around I found this diagram. The red arrow is the pressure relief valve but what is the blue arrow. The blue arrow is where the fluid is leaking out of. I was able to put a socket on it and it wasn't very tight but it turned about 1/2 turn but I didn't get a chance to run it to see if that fixed the leak. Can someone tell me what part the blue arrow is?