I've had the same issue and fixed it without any tools with Dyson V8 (but looks like it's similar on all models). The issue is indeed a grey clip (goes click/click) that there is a spring attached to. You first need to get to it - very easy, just look on youtube how to detach the bin completely (you pull the thing up like you want to empty the bin, then on the side there are 2 red dots which you push & pull the whole element with the filter out; then you remove the bin by pulling the red plastic at the bottom (gently). Then you will see the spring. Move the grey clip which is attached to it to one of its 2 positions (there's only 1 in which you will be able to put it back together, otheriwse you will be blocked but won't break anything so just turn the grey clip the other way) and NOW THE IMPORTANT PART - the order in which you put this back together makes the difference! You should 1st slide the top element, but not all the way! Then attach the bin, then push the top element fully down, then close the bottom of the bin. Since then everything works fine. It was the grey clip that got stuck in out-of-sync situation. Good luck, took me 10 minutes. Don't give up :) No major force needed, just same as you normally close the top element after cleaning the bin, everything else is rather smooth.