Epson LX 300+II Reference Manual page 20

9. Slide the left sprocket so its pins are aligned with the holes in
the paper and push the blue lock lever to lock the sprocket in
place. Then slide the right sprocket to match the width of
your paper, but do not lock it. Move the paper supports
midway between the two sprockets.
10. Make sure your paper has a clean, straight leading edge.
Open the sprocket covers. Fit the first holes of the paper over
the sprocket pins and then close the sprocket covers. Slide
the right sprocket to remove any slack in the paper and then
lock it in place.
Note:
Remove any remaining slack by gently pulling the paper from the
back.
20
Paper Handling