the radio has been sitting for years on my shelf it transmits fine but has no sound the time before last time i checked it out the sound was in and out all scratchy like it was dirty so i just put it up and now i took it back out and gonna have it fixed but would like to know why there is no sound at all is it the knob is it something more if i key another radio up the needle moves its the older one with the single volume knob if its just the knob can anyone point me in the right place to get the knob for it