Once you determine what is going on then you can determine if it is worth repairing not.
I also have a 3100cn, actually it is my wife’s. Earlier this year there was nothing meaningful on error 007-340 both on a forum and the web, but recently, there is more on this. When I turn on the printer, it runs through an electronic self test, the toner cartridge drum rotates to the next cartridge, and then error 007-340 appears.
Is this the same action anyone else has seen?
Does it seem similar to the vertical transport unit failure you had?
What and where is the vertical transport unit?
How much was the replacement?
I called Dell and the help was less than stellar as my printer was out of warranty. I have no problem working on the printer myself.
Please HELP, anyone!