It's not just Fender all the big amp companies are having trouble. Some of it is build quality, which can be a hit or miss, some internal parts quality and some tube quality. I have a DRRI and really like it but it had a noticeable hum coming from the PT and telegraphing through the speaker. First thought it was a tube, nope checked that out. Then I replaced the cheap(crappy) Illinois filter caps, with better quality F&T caps. Didn't fix the problem, but it was worth the effort. I could feel a vibration in the PT and thought why not up grade it to a Hammond PT, that did the trick. Now this amp is as quiet as a mouse and sounds great. No other issues.