Re: stuck receiver....
Put the pin back in it hook up to the boat and take it for a 10 mile drive , that will loosen it right up
+1 That usually works! ^^^
Chaining it to the tree does not tend to keep a good tension on it.
Chain does not stretch much!
I have used a 100 ft length of 3/8 or 1/2 nylon rope.
Go around the ball and the tree 2 or 3 times.
This will give you 4 or 6 length of rope from the ball to the tree.
Now pull forward and put a good stretch on the rope and then set the brakes and chock the wheels so it is not pulled backwards.
Tie another piece of rope around the 6 strands and tie the other end to the hitch with just a few inches of slack as a Safety Rope to catch the ball when it comes loose.
They usually do not
Sling Shot very far, but better to be safe.
Do let anyone stand behind the hitch once the rope in under tension.
Hammer Up and Down, Left and Right.
Once you get it to move under tension it should be out a minute later.
This might sound like a funny home video in the making, but it really is not all that crazy!