Don't worry about it, clean it up carefully, put on a new oring and some vasoline onto the o-ring area to allow it to slip down without popping up or damaging the ring and you'll be fine... I did the same to several injectors while replacing the 1st engine, half the ones on the car don't have that gasket thing
Aftermarket performance injectors don't even have them :th_thumbsup-wink:
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Lucas 42.5 pound/hour Fuel Injectors[/FONT]
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Siemens 60.0 (65.0) pound/hour Fuel Injectors[/FONT]