All I can say is that mine are extremely stiff and "pushing" them in and out is not really possible without a bunch of pressure-so I did not push them at all. I just added the correct mass and went with it. They are TC Sounds VMP 18 and they are all pretty much exactly the same. Call AE and ask then, they should know for sure. Good luck.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.
Pictures would help