I don't have any particularly special ideas for a "copper" chassis.
But like all the metal radio chassis that I do, I simply wash them in the kitchen sink and blow dry or put in a pre-warmed oven.
I have no experience with TVs.
For heavy corrosion or dirt you might consider a wet SOS pad. With the soap they are usually very gentle to metal. Be careful not to wear through the plating. If the pad tends to scratch the finish, you might consider finer steel wool.
Keep in mind that whatever steel wool product you use may leave bits of steel around electrical connections. Certainly keep away from potentiometers and switches. Hopefully you can just Brasso the chassis without the aid of heavy steel abrasives.
T.