Very bad rattle issue fixed!! Went to dealer today to get the issue sorted, when Bass would hit there was a horrible rattle coming from back end. If anyone else has this issue here is what the problem was. Once sub box is exposed and loosened completely flip box over and check mounting brackets...there should be 3 mounting brackets on box...plastic..we added some rubber gromits between the bracket and body of the DD....the brackets were vibrating against body from bass...the rubber between the bracket and body don't allow it to touch once tightened. Hope this helps anyone who might have same issue.