I went to play my DRRI today and wasnt able to get any sound from the amp! I tried all inputs on both the normal and vibrato channels...no sound. So I plugged into another amp to make sure my chord etc was ok and got sound from the other amp. The power light on the DRRI was on and the power and rectifier tubes were glowing a little so I figured it wasn't the fuse. I tried cycling the power a couple of times and still no sound so I decided to play through another amp for my practice session. When I was done practicing I turned back to the DRRI. I powered it up again and got no sound. I powered down and on a whim decided to try wiggling and pushing the tubes up into their sockets. Powered back up and I was back in business. Unusual experience....or forget about it and rock on but remember to reseat the tubes next time I get no sound?