The Historic District

Late to the waffle iron party. I have one also, late 20's, has the little gauge in the top middle, also has the original cloth cord.

It has two temperature settings: Very hot, and off.

For some reason, the first waffle is a disaster, after that they are fine. The standing rule in the house is do not use the waffle iron. My youngest tried recently, took me an hour to clean it.

Hey kids, look in the freezer. Yellow box with the word "Eggo" on it.

These are about as simple as an electric appliance can be. There's no temperature control or switch, so the thing is just going to keep getting hotter until the power source is removed. When you use it, just remember that and be sure to keep it clear of anything that could potentially melt or burn. As another poster mentioned, the voltage in the wall was slightly less in the 1920s, so you could always operate it with a variac and turn the voltage down to about 105-110V.

I wouldn't worry about a grounded cord or modifying the design. It basically is what it is. Just use common sense and you'll be ok. Remember - these were designed to be used for a short period of time and disconnected.