Kogan KAFSHXXGRYA User Manual page 19

If there are any air pockets between the sonar senor
and ice, or air on the water below ice, the unit will
not work properly and will require you to try another
spot, or cut a hole in the ice to use.
NOTE:
*** To remove the sonar sensor from the frozen
ice, gently tap sonar sensor at the base with your
hand. If it will not come loose, spray a small amount
of water on the ice surface around the base and
repeat above step until the sonar sensor is easily
removed.
Never use a blunt instrument to strike the sonar sensor
as this may cause damage to the sensitive internal
electronics.
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