Epson AcuLaser CX37DN Series User Manual page 244

6. Stick the label to the front of the 550-Sheet Paper Cassette Unit as shown in the illustration below.
Note:
The label is supplied with the printer.
7. Reconnect all interface cables.
8. Reconnect the power cord, and turn on the machine.
9. Declare the Tray 3 in the Windows printer driver (Properties/Configure tab).
Epson AcuLaser CX37 Series Printer/Copier/Scanner User's Guide
Installing Accessories 244