I'll try and keep the story short and give you as many details as I can. My entire car audio system is a T.M.A (total mobile audio, subdivision of JL Audio) setup from a "brick and mortar" shop (as the EDU calls it). I have: 2 speakers in the front (I believe 6") 2 speakers in the rear (6x9" I think). 12" Subwoofer (I don't know the specs on it but I can find them online if they're needed) 4 channel amp (specs here: http://tma.jlaudio.com/products_amps.php?amp_id=423 ) My headunit it a Pioneer 3900MP. Everything has worked pretty well for the few months I've had it and overall I've been pretty satisfied with the sound. I expected a little more for what I paid but a lot of the costs were labor and materials (wiring harness / cables / box for the sub). A few days ago I noticed my sub wasn't working so I spent some time trying to figure out what was wrong with it but I haven't came up with a solid conclusion yet. It works "when it wants to" which leads me to believe that it may have a short in it. I swapped the sub into my buddies car and it played fine for the few minutes it was in there so I'm not sure if it has a short or what. I thought maybe my amp was messed up and not providing enough power but I plugged in his box (2 12" Kicker subs) and it ran perfectly fine. The protect light on my amp hasn't flickered / gone on at all so I don't think it's an amp issue. I have very little experience with audio equipment but I do know that the sub is capable of working, I'm just not sure why it's deciding to only work half of the time. If I very gently push on the center of the sub while it's running it will start to work but as soon as I take my hand off it stops. I've never opened up the box that the sub is in and I'm not even quite sure I'd know what to look for if I did. At this point I'm looking for suggestions on how to fix my current problem, OR a good (and relatively cheap) sub I can put in the box to replace it with. Is it easy to swap different subs in and out of the box? Thanks in advance for the help.