As a companion thread to the foam one below I've also got the same situation with this same dipstick about the dust cap being an "innie" on my 2121's verses the "outie" he put on them because he said he had to remove the dust cap to get the "thousands of an inch" tolerance in the gap between the voice coil and the magnetic structure. Once again he states that there's no sonic difference in the cap being in or out. And my response is the same... if JBL wanted them to protrube outward then there's a damn good reason they did it inward plus I told him to repair the speakers and make them look the same as when the were brought in to you. Alright all you guys who have the answers post them now!