Hopefully not expensive. Right now the 3pt works fine, just can't adjust the drop speed. My guess never used. I did find similar situations and seems I need to soak it w penetrating and have patience.
Found this post from google search on orange tractor site
Default Re:
BX2350. Three point linkage problem
The knob under the seat that controls the speed of how fast the 3 point arms lower also keeps the 3 point arms from lowering if the knob is fully closed (turned fully clockwise). If that knob is frozen, you may need to get under the tractor and spray the knob shaft with some penetrating oil and tap the knob shaft LIGHTLY with a hammer to loosen it up enough to get it to turn. When I say tap LIGHTLY with a hammer, I mean just enough to get the knob to vibrate a little to work any rust loose. Keep the knob shaft wet with penetrating oil, keep trying to work the knob loose and be patient. It may have been locked in position for several years and is now just needing some coaxing to get it to work loose.