Here in Ireland, the tester marks the area of concern with a blue waterproof marker so that you can be certain where he/she has found a problem. I'm certain that's little or no comfort to you, I just thought that you might like to know
Just to confuse things further, in Northern Ireland the tests are more akin to the rest of the UK, but are done at government test centres. As for the advisory, the seal around the back of the swivel ball is leaking, you will usually see where quite clearly. Not a difficult job, but a bit heavy/messy. plenty of videos on t'internet.