Casio XJ-450 Service Manual & Parts List page 23

3 Remove two screws (S3) in the filter unit.
4 Remove the remaining screw (S2) in the back panel.
5 The back panel can be removed together with the filter unit.
6 Remove one screw (S12), and then the terminal panel for
audio.
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Screws (S3)
Screw (S2)
Screw (S12)