I think you got short changed in the DIP tube department. 1/2 the heater isn't enough. Time to go above GE for complaints, meanwhile I think you need a longer tube.

How a water heater dip tube works and what it looks like.

Length of dip tube? - Self Help Forums

Cut to length DIP tube
Law Supply - Water Heate Parts and Accesories

That dip tube being only half way down the heater is not enough. Admittedly, I have only pulled a few dip tubes, but they should go almost to the bottom. That swirl action is to get the water moving around the heat source so that it all heats evenly. I don't use GE water heaters so I can't speak to customer service.

Sorry, I didn't see post #21. My browser dropped me on the second page.