American-style waffle irons are used to make traditional waffles, which are thin and crispy with relatively shallow pockets. This means they cook fairly quickly, too. The savory batter used for this type of waffle makes it particularly well-suited to making special shapes like hearts, or for use in place of bread for things like breakfast sandwiches.
Most waffle irons have removable plates. Open the waffle iron and remove the top plate. You should then be able to see the heating coil. Plug the waffle iron in for about 10 seconds, and you should see the coil get hot. Compare it to the bottom coil; they should be about the same. If they're not, then the coils could be defective. If the coils seem equally hot, the top coil may have shifted so it's no longer close to the plate.
That said, quite a few users say that this waffle maker isn't as sturdily built as previous versions of the same model, and that if you don't get the top heating plate aligned just right, it can fall off -- an injury hazard if the plate is hot. The top of the G48TD also gets very hot. Some use pliers to bend the metal clips that hold the heating plates in place, which helps them line up better -- or you can just use an oven mitt to protect your hands.