Brother HL-2600CN Service Manual page 336

I-7 White Line (2)
Phenomenon
Vertical white line appears from the leading edge to the trailing edge of the printed image
as shown in print sample (7) of
Main Causes
The dustproof glass of the optical unit 2 is smeared with toner or foreign particles.
Countermeasures
Clean the dustproof glass.
1) Remove the OPC belt cartridge and toner cartridges. (See
VI.)
2) Remove the dustproof glass from the optical unit 2.
3) Clean the dustproof glass. (See
I-8 Vertical White Band
Phenomenon
White band appears in the vertical direction of printed image as shown in
of Fig.8-2.
Main Causes
Silicone oil adhering to the transfer drum 2.
Transfer drum 2
Adhered silicon oil
Countermeasures
1) Wipe off the oil adhering to the transfer unit 2 and its perimeter.
2) Replace the transfer drum 2 with a new one. (See
3) If the oil adhesion is excessive, replace the OPC belt cartridge and drum cleaner 2
with new ones. (See
Fig.8-2.
Section 1.2.5 of Chapter
Transfer unit 2
Fig.8-7
Section 2.1 and 2.5 of Chapter
Section 2.1 of Chapter
VI.)
print sample (8)
Drum cleaner 2
Section 2.8 of Chapter
VI.)
Transfer drum 2
VI.)