Printronix P6000L User's Reference Manual page 30

Figure 2-6. Forms Thickness Adjustment Lever
Vertical Position Knob - The Vertical Position Knob, shown in Figure 2-7, moves the paper
up or down. The platen must be open (Forms Thickness Adjustment Lever fully raised) to use
this control.
Figure 2-7. Vertical Position Knob
2-10 Operation