Hi there. I own a Fender Rumble 150, and it does strange things. I would like to possibly fix it myself. "The Strange" 1. Volume knob is all the way down, yet it continues to be LOUD. 2. When messing with knob, its scratchy, and levels fluctuate wildy. Sometimes i can just tap it, and it can go from very quiet, to very loud, and vice-versa. 3. If i give even the slightest tap to my bass output...not the amp input...the bass output, it can, and quite often will pop very loud. I know its not my bass or cord, as i have plugged into other rigs, and nothing happens. It plays great. 4. It hisses...oh does it hiss. I use a tascam dr-22wl to record, and that hiss is very prevalent in my playbacks. I have yet to pull the head, as i really have no business messing with that stuff, and am afraid to do more harm than good. I was just wondering if anyone recognizes these symptoms, and can diagnose? Really trying to avoid spending alot of money and maybe correct the problem myself. And, too, i figure i need to learn some of this stuff, as i have gotten pretty serious about my playing recently. I know this is a good amp for someone in my situation, so id rather not see any "get a better amp" replies...though now i most likely just invited a whole slew of them in. Thank you in advance for any help that can be offered.