Reassembling the lower intake and getting ready to put the injectors back in. Noticed that there are these little yellow plastic retainers just below the O-ring. How critical are these? Many of mine are broke and missing pieces (looks like previous owner used pliers to remove and broke them and put them back on)

 

I went ahead and installed the injectors with the broken and missing nylon retainers. No problems so far. I assume that their purpose is to hold the o-ring when pulling the injector out to prevent tearing.