I have changed a lot of these injectors over the years & have not had this problem personally but have got referrals from other shops with this problem.Usually the deformed or out of round copper washer was from the cumbustion gasses overheating it sense it did not seal properly it could not dissapate the heat back to the cup IMO.I always have "seated" a new injector with a soft face dead blow hammer & you can hear when they seat properly.Also I have tried different lubes for the o-rings & the best that I have found is the Lucas motor oil additive, goes right in.I have also notised the upper hold down bolt would make a 1/2 a round or so.