Oki 490 - Manual (Page 50)

50 Microline 490/491 User’s Guide
8 Adjust the position of the right tractor to center the holes in
the paper on the pins. Then, close its tractor cover and push
back the lock lever. Do not stretch the paper.
Note: If the paper is too loose or too tight it can cause jams.
9 Reinstall the sheet guide.