So, I just purchased a 1976 Ampeg V4B. There are a couple things that need to be addressed, and I wanted to see if anyone else has had these problems or knows what they might be. The first problem is that the amp hums even when the volume is all the way down. Is that normal? I am not familiar with these amps yet. It appears that all of the Electrolytic caps have been replaced fairly recently. The can multi caps appear to be the originals. Not sure if perhaps replacing the can caps would help with the problem. I've tried adjusting the hum control on the back, and it seems that even at it's sweet spot it still hums pretty good. The other main issue is that the midrange pot seems to hum really badly when I cut or boost, when it's dead center it's fine (or doesn't hum as badly anyway). Would it be worth replacing the pot, or is something else most likely failing which is causing the hum? Thanks in advance for any help guys.