What I'm seeing while shopping is there are two different kinds of filters one with a hole and one without. I'm thinking the filter works with both types, just remove the nut, pops right out. I contacted the seller and he said he's never had a problem and I could send it back if I want but I think it's OK because it mounts up perfectly. What I'm starting to think is the guy I purchased the cover from put a screw from another saw on it. What do you guys think? I've ordered a replacement screw already, or return the filter?