Re-installing injectors

2001 Venture.
I'm putting everything back together. I put new o-rings on the lower injectors (didn't remove them from the rail). The o-ring kit came with 2 sizes of o-rings. Half are a little fatter than the others. Without taking the injector off the rail, which o-ring should I be using on the lower part of the injector? I used the thinner o-ring since the looked the same as the old ones and one injector will not stay in the LIM hole. If I'm using the right o-ring then do I need to bend the support a bit (it may have been tweaked during removal) so it applies more pressure on the one sticking up?
I forsee a fuel leak if I leave it as is. I can see part of the o-ring on the one that sticks up.

Lube 'em up with 5w30 oil! You should also have the rings that go around the neck of the injector? No big deal if you didn't get those, just wanted to make sure you know what they were.

The whole idea is to keep the injectors from leaking. The upper and lower seal are very close to same size. Use the one that works. The injector rail gets held down with the clamp screws and injector can't really get away once the rail is held down.

John

I got them in but the upper right one wants to lift back up a bit so I think the support may have been bent a tad. I'll pull it back out and see what I can do. I did read somewhere (maybe here) that you want the injector to be able to "spin" freely. is that a big deal? I'm thinking they won't spin much if I use the "fatter" 0-ring.

Ya, you should have 'em stuffed in there so they can move around when twisted. Lube does the trick. Twisting them back and forth helps them seat.

Thanks John.