Tube pre amp problem?? Help??

Hi all, I have a New Dared MC-7p preamp and to make a long story short, went to roll in a 12AX7 and when I turned it on, a loud squelching shrill noise came out of the right speaker then nothing, silent out of the right speaker. I quickly turned it off and put the stock tube back in and again, nothing out of the right speaker. I was horrified that I may have blew up the speaker X-Over or something as no sound at all was coming out. So I hooked up my Dac/pre to see where the problem lies, and thank goodness all plays well. So something happened to the preamp I guess but what?? I took the bottom cover off to look for fuses but only see about three tiny ones that look to be hard wired in, and they don't look blown but cant tell. I'm so mad I am ready to fire sale the pre. Any idea of what it could be if not a fuse?? I sure am not going to send it back to China. Look for a good deal on the Gon. I'm going to stick with SS.