Usually this is something you can take care of yourself. If you are capable of locating and cleaning the condenser coils, clean them. This is the main cause of problems in refrigeration. If a dirty condenser coil is found by me, I can generally clean them within a one hour service call provided access to the coil is not restricted.
One of the tricks of the trade is the fact that most ice makers won't harvest the ice until the freezer temperature reaches 0 degrees, well below the 32 degrees needed to make the ice. The first step to diagnosing an ice machine is to make sure the freezer temperature is below 0 degrees. If it is not, find out what that problem is (example: dirty condenser coil)
If the temperature is below 0 degrees, then other troubleshooting must be done to insure proper electrical connections, water flow, etc.
Freezer not defrosting properly
The three main mechanical failures are:
Defrost Timer
Defrost Terminator
Heating Element
Depending on which component fails, the cost of repairing this usually runs between $125 and $225
Water making mess in fridge or on floor
If water is not draining properly, The evaporator section must be dismantled and cleaned to insure no restrictions in the drain line. Generally can be repaired with service call and 1 additional hour.