HP 3900 series - Manual (Page 47)

Caution Do not leave the print cartridges outside the printer for more
than 30 minutes.
Cleaning instructions
1.
Lightly moisten a cotton swab with distilled water and squeeze any excess water
from the swab.
2. Wipe the face and edges of the first print cartridge with the cotton swab.
Caution Do not wipe the nozzle plate. Touching the ink nozzles will
result in clogs, ink failure, and bad electrical connections.
1 Nozzle plate
2 Face and edges of print cartridge
3. Inspect the face and edges of the print cartridge for fibers.
Repeat steps 1 and 2 if fibers are still present.
4. Repeat steps 1 through 3 for the second cartridge.
5. Wipe the underside of the print cartridge cradle walls with clean, moistened
cotton swabs.
Repeat this process until no ink residue or dust appears on a clean swab.
User's guide 45