Suddenly, our ice maker has stopped functioning properly. It still makes and drops ice cubes but for some reason the bottom of the ice tray develops a thick layer of ice.This is turn causes all the loose cubes to freeze together in a large lump. Any suggestions on what he problem might be?

The problem is that either the solenoid is leaking water or you need to do a simple adjustment. The water level is controlled by the time the switch is depressed by the plastic cam as it rotates after dropping ice cubes. You take off the end cap and you will see an adjustment that has "+" and "-" and you turn a Phillips screw with a spring around it. Try 1/4 turn at the time until the problem stops. The water level can be changed by an increase or decrease in water pressure. Here are some manuals: https://dl.dropboxusercontent.com/u/8010163/GE_Profile_Artica.pdf
https://dl.dropboxusercontent.com/u/8010163/GE_Profile_Side_by_Side_refrig.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20Icemaker%20Troubleshooting%20Service%2 0Manual.pdf (Ice-makers are made by about three companies for all brands)
https://dl.dropboxusercontent.com/u/8010163/5995436457-Ice%20Maker%20Service%20Manual.pdf
https://dl.dropboxusercontent.com/u/8010163/How%20to%20use%20Test%20Equipment%20Service%20Manu al.pdf