I went to turn on my Peavey 6505+ yesterday, and I waited for everything to warm up. I heard no sound coming from my amp for a while, so I checked all my cables. Everything was plugged in. I checked the power tubes and none of them were lit up. I removed the plate that covers the preamp tubes and 4 out of 6 of them are lit, I am not sure if they are all supposed to be lit or not. I checked the main fuse, and the 5 other fuses inside the amp and they are all fine. I have had the stock Ruby tubes since I bought the amp new about 2 years ago. I was thinking about going out and buying some new ones to see if that will fix the problem, but I don't think it will since all of the old tubes were working fine the day before, with no signs of them giving out at any time. Maybe one of the tubes died and the rest don't light because of it. I am not sure what to do. Any help is appreciated, thanks.