Ok, here is an update. My tech finally recovered from his hernia surgery and had a chance to get a detailed look at my amp. He did find 2 tubes that were going bad. He also said that the last guy who changed my preamp tubes had them in the wrong place. Not sure on the specifics, but he said they just needed switched around. So, I had him re-tube the whole thing $$$. I had one practice to try it out before my last show. I didn't try the Telecaster bass with the new tubes yet. I didn't want to blow anything up before the show. But, at the show, I received 4 compliments on my bass tone. I am one deaf SOB, so I am wishfully thinking that the new tube job is responsible? I am planning on trying the Telecaster bass at our next practice. Keep your fingers crossed.