Hp 4000t

[MARKT]

I am getting light grey line on left edge of sheet all the way from
top to bottom. The line is 1/4" wide and begins 3/16" form edge of sheet.
Machine is about 10 yrs old and has never had any parts replaced.
Any suggestions are appreciated.

[silver]

There are two likely causes of this problem the toner cartridge, and the fuser unit. I would recommend replacing the toner first, and if this makes no difference, then to remove the fuser unit and examine the upper fuser roller.

This page shows how to remove the fuser unit from this printer:

http://www.printertechs.com/tech/mkinst/mk-4000-2fuser.php

The page goes through the fuser like a clothes wringer, and compare the upper roller of the fuser to a page with the print defect on it, and if there is a mark or damage to the fuser roller then replacement is required.

If it is neither of the above, I will be very surprised, but post again and we will check some other things.