See also:

Setting the playing speed (only when the audiobook is playing) (type D audio)
Each time you briefly press (the “RPT” button) while the audiobook is playing, the playing speed changes in the following sequence. ...

Non-turbo models
...

Replacing the air cleaner element
Replace the air cleaner element according to the maintenance schedule in the “Warranty and Maintenance Booklet”. Under extremely dusty conditions, replace it more frequently. It is recommended tha ...