I just bought this and the 12" speaker is vibrating pretty bad. If I put my finger on it then it stops while I'm playing but as soon as I let go it starts back up. When I hit the string it sounds like air is being pushed out. I can't find any holes or tears in the speaker and it's hooked up inside pretty tight. When I have the speaker out of the combo (still plugged in) if I touch pretty much anywhere or push the speaker in it sounds perfect. Just wondering if any one else has had this problem and if there is a fix. And please don't say "Well, just put your finger on it while your playing."