Oki 490 - Manual (Page 49)

Maintenance 49
Note: The movement of the left tractor (as viewed from the
front of the printer) is restricted to ensure that the
paper covers the paper out sensor.
5 You will find reference marks (1 in illustration below) on the
printer for the two most common paper sizes:
ML490: ML491:
6 Move the left tractor to the position to match your paper size
and push back on the lever to lock it in place, then move the
right tractor to fit the width of the paper.
7 Open the tractor covers and place continuous forms paper on
the first two pins of either tractor, then close the left tractor
cover.
Important!
You must keep the number of paper holes engaged on either
pin the same. If you don’t the paper will jam.