Laser heads can misalign though (not sure if Xerox does that). Your Xerox® WorkCentre 6515 printer was launched 9 years ago and is not sold anymore. It's very possible that they changed their practices since then and/or that the price point is high enough that they wouldn't do that (it's aimed at professional customers after all).

Either way after a quick Reddit search there seems to be irreplaceable parts on that printer too. For example the fuser which is allegedly not user-replaceable.