This is really ironic but I am having the same issue with my 2 new MP 40qd I purchased a couple months ago. I've tried numourous things to get them in alignment but they keep wobbling and falling off, then eventually after numourous attempts to get it alighned it will work for about a 3 days to a week and eventually fall off. I used the correct spacer for 12mm glass, I had the non QD so I'm very familiar with this product and never had this issue. I don't have any snails small enough to fit threw the gaps on the side, and I use the sponge filters as well and I've literally watched one just wobble off. I was about to send an inquiry to Echo Tech in regards to the issue. If any one has any ideas, to fix or resolve the issue please let me know.