Wingsfreak9 10+ year member
CarAudio.com Veteran
this same thing happened to me when i was installing my 5.25's. I went to mount the new speaker and i over tightened and snapped off one of the screw heads leaving me with only 3 screws holding the speaker in place. I powered it and that one speaker sounded absolutly awful with that rattling noise so i drilled a new hole thru the mount and got new screws and it works perfect. good luck hope this helps