Racecarhauler--new/reman injectors come with the copper seal and o-rings already installed, so replacement by the dealership shouldn't have even been an issue. AFA cleaning the injector cup, all I've ever done is cleaned them with towels however is you have one leaking exhaust then it's possible you'll need the tool. Installing the copper crush washer should be done every time you pull and replace an injector. The o-rings I've reused with no problem but they come with the kit so why not use them. Changing them on every injector on one bank just isn't necessary.

If the injector wasn't seated into the cup properly the truck probably wouldn't be running enough to drive.