I need some guidance as to the problem with my Icemaker.

I have a Kitchen Aid Ice Maker Model # KUIA18PNLS11

Everything is running fine (no funny noises...I have 2 other same exact units), I have reviewed the troubleshooting guide in the operating manual and nothing has helped.

The water is running over the freezing plate, but not freezing or making ice.
I have tried bringing the machine down to colder temperature by adding ice into the bin...and very little ice is then made. I would say the cubes are about 1/4 " thick...cutting grid is working fine, drain cap is secure, no service light is on. Have tried re setting the unit by leaving it off for 1 week so it could cool...but nothing is working.

What parts should I think about replacing?
Is it the compressor?
If so, should I buy a new unit?
Or is it something related to the freezing plate???

Please advise.

Captain David