Right up front I must apologize for my ignorance, as I know next to nothing about tube amps except for how to turn them on and off. I have an Ampeg SVT-3Pro that I almost never use. It's remained in my closet for almost a year. It worked fine when I put it away. I pulled it out today, and when I turned it on I got a loud squeal that escalated in pitch and volume until it disappeared. Now there is only the faintest volume coming out of the speakers when my bass is plugged into the front input jack. If I plug my bass into a Sansamp and run the signal into the Effects return jack the sound comes out of the speakers just fine. Does this sound like a tube failure? A faulty input jack? Something more nefarious? Any help you can provide would be so appreciated! Also, anyone know of a good Ampeg tech in the Houston area? Thanks!