Gerber HS15 Plus User Manual page 23

All other materials can be fed over the idler roller, as shown below.
To feed and align the material
1. Feed the material through the plotter as shown in the appropriate
diagram, according to the type of material you are working with.
2. Place the holes in the material over the adjustable sprockets on the
drum first (toward the rear of the plotter), making sure to match the
three closely-spaced sprocket pins and holes.
3. Place the holes in the material over the fixed sprockets at the keypad
end of the plotter, making sure to match the three closely-spaced
sprocket pins and holes.
4. Center the front bail arm over the fixed sprockets and secure into
place.
5. Adjust the sliding sprockets at the rear of the plotter slightly forward
or backward to accommodate small differences in the material
width.
6. Securely close the adjustable bail arm over the adjustable sprockets.
Materials and Tools 15