A picture of what you had done might help some.
I would consider having a good
weld shop fabricate a couple of 2 1/2" square by 1/4" or even 3/8" thick plates With the proper sized hole drilled in the center for the pin. Place them on the outside of the receiver hitch tube over the existing oval shaped holes. Hold them in place with the proper sized bolt and have the plates welded to the receiver tube. You would then have a wall thickness on the receiver tube that is at least twice what it was originally. Instead of using a pin, I would use a grade 8 bolt and nut to hold the ball assembly in place. Just a thought.
I would also check to make sure the entire receiver hitch assembly is still bolted tightly to the frame of the TV. The way you describe the noise, there could be more than one problem.