Have followed all of the methods on the first page of this thread, and it seems like I'm almost there, but I've been almost there for several days now.
I've gotten to the point where I can run the configurator OK, but it gets to the port selection page, and I don't know which USB port to choose. I have chosen several (most recently mfp4) and then continue on. I then run the "test". It says "driver found", but then "can't find devices on mfp:/dev/mfp4".
I then ran the Ubuntu printer app (under System-Admin) and went to the troubleshooter. It gave:
"printer "scx4x21" not owned by root" and "Printer 'scx4x21': none
:Failed to get parent
Any help greatly appreciated!