I just replaced both of these parts on my 6700DN. Not sure which of the two made the difference but I can confirm, at least in my case, that replacing one or both of the above parts clears this error (391.302.02).
I have a Xerox 6700 which will not print. The display shows:
System error. User intervention is required to Power Off/On the machine; service is required if the problem persists. Print service is not available.
I have restarted several time, left the machine off overnight, and replaced the maintenance kit.
None of these steps have helped. Is there somethign else I can try?