Lenovo C2 Series Hardware Maintenance Manual page 58

For models C320 and C325 refer to the illustration below. (17 screws)
Step 10. Disconnect the data cables from the motherboard , remove the 4 screws that secure the speakers
to the chassis and lift up the speakers to remove them.
For models C220 and C225 refer to the illustration below.
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Lenovo C2/C3 SeriesHardware Maintenance Manual