Question about Samsung Sl-C460w

Hello, I have a Samsung Xpress c460w. In the last two days I have replaced the fuser unit (after the print image became bad and a message came up), then the next message came up (replace transfer unit) and because I am so generous I also replaced the waste toner container. Then came the message "Transfer ribbon error", so I ordered this too and put it in. Unfortunately, the message still comes up.... In the Tech Menu (key menu, back, left, right, Ok, Stop/clear, menu) I have already deleted all error messages and reset the machine. I still can't print... Does anyone else have any ideas?