I've read some other reviews from people saying the filter doesn't fit. When I first tried to insert a filter I had the same problem. I'm not sure if it's because it's a bit smaller or because the rubber coffin is made of a stiffer material. However what I have found is if you lay the filter on a flat surface - open end up - take the part that goes in, line it up just above the opening and push straight down. with a little pressure it slides without problems. It's a little denser than the…