HP Laserjet 1200 - Manual (Page 129)

EN Cleaning the printer 127
Cleaning the printer media path
If you are experiencing toner specks or dots on the printouts,
clean the printer media path. This process uses a transparency
to remove dust and toner from the media path. Do not use bond
or rough paper.
1 Load a transparency in the priority input tray.
2 Make sure that the printer is in the Ready state.
3 Press and hold the Go button for 10 seconds. The
transparency feeds slowly through the printer. Discard the
transparency.
Note After holding the Go button for 10 seconds, each of the three printer
lights blink until the cleaning process is complete.
Note If transparency film is unavailable, you can use paper, but you should
perform the procedure 2 or 3 times to ensure proper cleaning.