Epson DLQ-3500 Reference Manual page 125

2. Set the paper-thickness lever to the appropriate position for
the type of single sheet you are using referring to the table in
"Adjusting the Paper-Thickness Lever" on page 1-5.
Normally set it to AUTO.
* paper-thickness lever
3. Insert paper into the automatic sheet alignment unit so that
the tip of the paper goes behind the rollers of the unit. The
printer automatically aligns the paper, recognizes the right
and left edges (the width) of the paper and starts feeding.
Options and Consumables
AUTO
9
8
7
6
5
4
3
2
1
0
-1
5-17