Advanced Bionics M Waterproof Battery Mode D'emploi page 24

To insert the new O-Ring, place a portion of the new
O-Ring in the M Waterproof Battery mounting groove
on the case. Take care to match the shape of the O-Ring
correctly with the shape of the M Waterproof Battery.
While holding the O-Ring in the groove with one hand,
carefully stretch the remaining portion of the O-Ring into
the remaining groove.
Run your thumb over the O-Ring to make sure of proper
insertion. Extreme care should be taken to make sure
the O-Ring is level and secure in the mounting groove.
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