JVC WR-MG77U Procedures For Using page 4

O-ring
Rubber ring for waterproofing.
Check to ensure that the ring is not twisted and foreign materials are not
attached, followed by attaching it to the designated position.
Cotton swab
For cleaning the O-ring groove.
Press it lightly against the O-ring groove and move it around the circumference
of the groove.
Cotton swab
4
O-ring
Dirt, sand, salt
crystals, etc.
Hair, thread, etc.