I followed the excellent repair video on Appliance Parts Pros and everything worked out just fine. It was easy to replace the rollers. The video explained exactly what I needed to do and showed exactly how to take out the rack and replace the rollers.
Although only one roller was broken, I replaced all 4 because the others would probably need replacing soon anyway. If you have a similar problem with your GE dishwasher, just watch the video and you'll be an expert repair person in no time.