I was running my Hartke 3500 head into a SWR Goliath I and suddenly it smelled like a campfire. I had a small amount of smoke coming from the rear port. Where do I start? I don't know what went wrong. I have a little knowledge about speakers and cabs but I really don't know where to start. I also don't know how to test individual speakers crossovers or tweeters. Please HELP!!!