Ok, so last weekend I was at my friends house with my amp (Ashdown MAG 400/410) and he was "tapping" (between tapping and banging) a beat out on the top of the amp when on his final tap a huge flash was emitted from the back of the head! So, I didn't get the chance to use the amp again until this weekend at band practice. When I started to play the VU meter would peak beyond the read with the input volume at almost 0 and me running through the low input. I also noticed that almost no air was flowing through the front of the vents in the head from the fans, although the room we played in was sweltering hot. So, I decided to let it rest until yesterday when I noticed that it was playing just fine with normal VU readings and fan flow. This being as reassuring as it is, still causes some to concern about the huge flash that went off inside the head, especially considering that the head is encased in the body of the cab (see picture). Any ideas about what happened and/or what to do?