I have two issues:

First Issue: The first page of the duplex page is fine. On the second page there are always "bubbles" on the print, it looks like the paper went a bit through water. If I print without duplex, the print is OK.

Second issue: On the end of each page there is a black area. I don't know why it is there, and it mostly appears only beginning from the fourth page that is printed.

I really like this printer, but it is so hard to figure the problems out, I am trying to solve both issues since a half month and I spend so much hours in solving them, but without any success so far