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I've had a problem with the screws, too. When it was taken to the Quik Lube for an oil change they did their 21 point check and didnt get one of the Air Filter screws out before pulling the top of the filter housing off. They broke off one of the corners of the filter housing.
I am wondering if they head of the screws are stripped making the phillips head screwdriver slip or if the threads on the screw are stripped? If the heads are screwed up just get a new phillips head screwdriver, put it on the head of the screw and tap it a couple times with a hammer and then try to turn it counter clockwise to get them off. If the threads are stripped making the screw turn but not coming out, put something under the screw and pry upwards as you turn the screw. You may have to go to the junk yard to get a housing.
Your air filter should be all right unless you have been driving on a dirt road behind somebody making lots of dust. I have an 05 with 36k and my filter looks like new.
This is a new one for me. I have never heard of the Air Filter housing scews being stripped. Post back and let me know what is stripped. Dave