Thanks Deejay, I have watched the video quite often in the past - I love it!!
I understand what is supposed to happen, but it appears to have defied the laws of physics.
I believe that since removing the deflector 2 weeks ago, it has become bigger.

I'm going to remove some of that growth, so it will again slot in easily.
I shall then quickly install it so that it can't grow any more.
Dave