Need help with injector reinstall.
 

I can't find a diagram in my workshop manual cd. Which slot do the retaining clips go into on the injectors? Upper or lower? I didn't make a note of this when I pulled them out. I can't see what purpose these clips serve in either notch. Should I press the injectors into the fuel rail first, then back into the engine or vice versa? I don't know what to do here. I think the right bank has them all in there snug now, but I can't make the fuel rail press down on them. Can I use Sli-Glide on the O-rings? Please help.