I was building the enclousure today and took out the PR's to see if they would fit in the holes I did with the jigsaw. I noticed that one of them has a looser suspension than the other one (not as firm). I placed them both in a table faced up and could tell that the "bad" one was more sunk in and the surround was lower too. I push it a little in and out by the tube area and could tell that it was softer, it was giving me less resistance than the "good" PR. These are AE PR 18-2100's going with a AV15X sub. The box they came in seemed to be in good shape. Is this normal? Is something wrong? Would it work fine or should I send it back for another one? I'm coming from a sealed sub so this PR sub is new to me. Thanks.