I have a Behringer Ultrabass BX3000T amp. Recently when I unplugged from the amp I ripped a collar type thingy out of the input jack. I'll explain: Someone gave me an expensive, fancy lead for Christmas which jams in really tight to the input jacks - the plugs are designed not to pull out of the amp by accident. I have always been careful to twist as I pulled the plugs out of my amp and bass because I was worried about damaging the inputs because the fit was that tight. Anyway, the other day I pulled the plug out of my amp and noticed that I had pulled a piece out of the jack. The plug had a little metal collar thing still wrapped around the bottom end of it (where the metal expands out and grabs tightly). I had to leaver it off the plug with a knife because it was so tight. I inspected it and it doesn't have any obvious lumps of solder on it or anything to suggest that it was ever attached inside the amp by any method other than friction. I tried pushing it back into the input jack on the amp but the fit is too tight to push it in with just my fingers. Also, it is sort of "ribbed" (not drastically, just some shallow stripes) at one end and I'm not sure anymore which way it was facing originally. So, I was considering using a soft mallet to tap the collar back into the jack but I'm a bit nervous about doing it in case I could do any damage... and especially seeing as I have no idea what its function is inside the jack. Has anyone had this problem before? Know what the part does - if it needs to be soldered in or anything. Any help would be much appreciated.