First hello to all in the tube section! My tube amp stopped working on one channel a number of months ago and being it was in a cabinet buried I didn't get to it right away. Well last night I dug it out and checked it out. Seems that one of the small 12aux tubes must have failed. It was an old Brimar set that I had purchased years back when I was doing a bit of tube rolling. So with a new pair of small tubes in place everything is working well. I did notice one of the power tubes plates getting a bit hot as it started to glow red slightly, so I shut it down got my meter out and set all the bias to .4mv DC which I hope is ok, the red plate cleared up. I was wondering about the chrome looking stuff on the tops of the main power tubes. I think they call that the getter flash, and I notice some tubes don't have as much on them as the others. Is this OK? I purchased this amp used have no idea the number of hours on the power tubes. I know I use the crap out of, everyday for years, at least a couple of hours a day for the most part some days more than that. They all seemed to bias ok, but how will I know when or if I need to replace them? It is a rather small amp at 50 watts a channel, and I use the 4 ohm output as it is driving a pair of Infinity Quantum 2 speakers. I don't over drive it rarely have I put the volume past 12 oclock. Is the lack of a log of getter flash an indicator that they are near the end of their lives. Right now it sounds great. This is the first time that I have adjusted the bias, but I have never seen the plates get red before. Thanks for any advice given.