The valve is leaking, you have to stop the leak with something, for Christof vaseline worked. So something that will stop the air coming out, but doesn't prevent you putting the needle in.
My own ball (europass) had the same thing, though when I first noticed the problem it was like your ball now, but in a week or so it was completely fucked up...
As for the situation when it magically stops leaking for you PE, it's because the valve happens to be in a position that it holds air.
Why not buy a new ball?
because you can fix it the way i said... if you want to throw out money, you can give it to me aswell
It will MAYBE fix the ball, it depends on how and where the valve leaks.
And I had this problem myself, so bloody annoying that I eventually bought a new one.
