so i bought some used injectors and they look good and everyhing but when i went to clean them off i noticed something that im not quite sure is right. if you look at the injector from the bottom there is a plastic cap and around that cap is a plastic ring, the ring came off fine except one was a little snug so i gave it a little twist to loosen it up and i noticed the plastic cap that it sits on moved aswell... twist and up and down. is that normal or did i **** it up??? they all twist but they didnt go up and down.

 

sounds like the pintle cap, should be fine.