Carver A-500X picks up stray radio stations

Hi, My carver A-500X amp picks up stray radio signals. It is plugged into an outlet with no oter cord plugged into that circuit, although some ceiling lights are using the same circuit. The amp itself does not seem to have a grounding screw, nor is the power cord grounded. Can I just connect any cable to one of the external plate screws and ground that cable? Is there any other solution to the amp picking up stray radio?
Move the wires.. Some wire, probably either a speaker wire, or an AC wire is tuning into the troublesome band.
I have had speaker wires pick up CB radio.
Try movingthe wires a bit. Find some lump of metal, and lay it around different places near both the speaker wires and AC wires.. When you find the spot the metal lump will 'soak up' the offending signal.
Th metal should be a heavy lump like a medium bench vise.. Or some other heavy solid chunk of metal.
A metal tool box full of tools would do too. A large AC motor.. Whatever... just so it is a lot of metal in a small package.

Once you locate the problem wire. you can eiter move it, or shield it.