You can try defrosting with a hair dryer. Make sure to defrost the far back of the unit. Dry up any water.
The ice maker frosts over due to most air getting into it. Inspect the dspensor flap to make sure it isn't stuck open or warm room air will get in. Inspect the gasket that mates the ice maker to the refrigerator door. You can view it by opening the other refrigerator door.
Lastly take a flash light and shine it at the bottom of the ice maker from the fridge side. Look inside the ice maker and look for a gap where the ice maker meets the left wall of the fridge and light shines through. If so, remove the screw holding the trim in the ice maker and run a bread of caulk along the seam.
Leaving the left refrigerator door open during normal use will allow air into the ice maker through the hole. Minimize leaving the door open.
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