I bought a Mesa 400+ 2 weeks ago,first week I jammed with my band,fuses kept blowing,I had to resort to my old amp to finish the practice. 2nd jam with it today,got new fuses and a surge protector,that fuse blew,so I replaced it and put the fan on high,then the second one blew,I replaced it,turned the amp back on,then a couple of minutes later I had a look at the back of the amp, The back row of tubes were glowing bright yellow hot inside,and would probably have gone red hot if left any longer.Yeah......I know tubes have a glow too them when operating,but these were extremely hot. New Peavy 6L6GC tubes were installed before I bought it. What could the problem be,is it something to do with the bias adjustment? Please help.