Hi everyone.  New to the forum and also to B&O.  My brother has a pair of Penta 6623 speakers with an issue that I am trying to fix.  The issue is... although one speaker works fine, the other one is not nearly as loud as the other.  Based on my research thus far, I suspect that the amp is not working in the low volume speaker.  Any suggestions on what to try to fix this?  Also, I've noticed that when I plug in the speaker in the outlet, it sounds fine for just a moment and then the sound gets faint relative to the good speaker.  I'm a newbie to speaker repair so appreciate any suggestions.  Thanks in advance!