I had a problem with one of my injectors, the O-ring had a chunk torn out of it. I noticed it when my fuel gauge started to drop followed by a strong stench of gas. So I looked under the hood and spotted a steady flow of gas down the side of my trans. I pulled off the upper and disconnected the wiring harness, Unbolted the fuel rail and exchanged the injector. It took me no time at all. I timed it and it took about 50min to do. Don't be intimidated, the press the wire clips to release them from the wiring harness. Pull the injector out and if the the o-ring does not come out with the injector, like you said, just role it out and back on to your injector.
