I have a Maytag refrigerator model #MFD2561HEW. The ice maker has quit working over the last several days. The activator bar/switch is definitely in the down/on position. Any ideas on what to look for?

Hello,
The first thing you want to eliminate as a problem is dirty condenser coils under the refrigerator. First, remove the front kick-plate and rear cover with the refrigerator unplugged. You will see the coils and the condenser fan which need to be sprayed with a good cleaner like 409 or Simple Green to remove greasy dirt. Get a wet-vac to get up water and wash out coils with a light spray of water using a water hose nozzle. Clean the blades on the fan, too.
After you clean it look for the water valve for the ice maker. It will be on your left and has a brown solenoid coil. It has two valves, both with brown coils. Check these with an ohm meter and you should have about 1-3000 ohms or so. They should be about the same. Just unplug the wires to test across the prongs on top of the coils. If they check out okay, replace back and front covers (clean front kick-plate before replacing) and plug it in and turn it on. Check the temperature after 24 hours and see if it's zero or below. It has to be around that temp to harvest ice. If it's that cold and still does not make ice you will have to check the thermostat in the ice maker and the micro-switch. Here are some manuals: https://dl.dropbox.com/u/8010163/Maytag%20Refrigerators.zip
https://dl.dropbox.com/u/8010163/KitchenAid%2015%20%26%2018%20inch%20Automactic%20I ce%20Makers%20Service%20Manual.pdf
The ice maker service manual should cover the ice maker you have because one company makes ice makers for several brands. It's a simple ice maker with only four electrical parts: the harvest t-stat, harvest heater, micro-switch that brings in water and keeps the motor running, and the motor. You will have to check each one if it's not the solenoids, but it's more likely that you will be able to fix it by cleaning it and replacing a solenoid as those are the most common problems.