Peavey Ultra plus won’t work after potentiometer cleaning.

[Ceredox]

I checked resistors 301 and 302 and low and behold they were both open. I replaced them and I now have sound! BUT there is hum and whenever i knock on the chassis or really anywhere on it, it pops VERY loudly. It also doesn't seem to be as loud as i would expect. I find it unlikely that there were two problems, originally but its possible. So i don't know whats going on. Does anyone know what would cause a pop like that? Unfortunately, i don't have fantastic equipment to check some of these things. I have a function generator, scope and a multimeter.

[Enzo]

whenever i knock on the chassis...it pops VERY loudly... Unfortunately, i don't have fantastic equipment to check some of these things.

Here is what you do, go get some takeout from a Chinese restaurant. Save the wooden chopsticks. Now use one of them to tap on the parts and connections on the board, looking for one or more that react.