There are 3 rollers in the printer that have circumferences of "about" 2 inches.
Transfer roller - 1.82 inches (46.3mm). This roller is in the printer
underneath the toner cartridge. It is very unusual for the transfer roller to
put dark marks on the paper that do not disappear after a few pages.
Paper pick up assembly - 2.17 inches (55.2mm). This is in the printer body but
is extremely unlikely to put a mark on the paper that does not disappear after
a few pages.
Fuser roller - 2.22 inches (56.5mm) this is also in the printer and is the most
likely cause.
To be sure you need to measure the distance exactly, "about" won't be close
enough.
If it is the fuser, and I suspect it is, the cost of a replacement is going to
be prohibitive. If you are very good at mechanical dissasembly or know someone
who is you could remove the fuser and see if there is a small spot of toner on
the roller. You can try to clean it off with a cloth dampened with isopropyl
alcohol but the roller is easy to damage.
Tony