Kenwood KRC-309S Instruction Manual page 21

Installation
I
Screwing the Faceplate on the Unit
If you want to fasten the faceplate to the main unit so that it
does not fall off, screw in the provided screw (ø4 × 16 mm) in
the hole shown below.
Accessory7
2CAUTION
Never insert the taptite screw (ø4 × 16 mm) in any other screw
hole than the one specified. If you screw it in another hole, it
will contact and may cause damage to the mechanical parts
inside the unit.
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