Most of the balls in use at the normal anchorages are installed and maintained by moor secure. Those that are not generally are marked private. There were some exceptions like BEYC who did their own maintenance. I have had two balls fail on me at night. One failed at the seabed and the other under the ball. Both were corrosion induced. I would not touch any of the BEYC balls now as corrision at the shackles on the seabed is a issue.
The current style ball chosen by boatyball is to tall for most cats and will damage the underside of the cat as well as keeping you up all night if you don’t have a steady breeze to keep the boat downwind of the ball. You can prevent this by bringing the ball up short and trapping it near the front crossbar so it can’t get under the bridge deck. If you don’t control the ball you could be hit with a rather large repair bill by the charter company. That big steel ring on top of the ball will do a job on the bridge deck.
G