To repair a Cuisinart toaster, disassemble it, locate the screws and use an appropriate screwdriver to undo the chassis of the toaster to get to the circuitry. Only do this if cleaning out the toaster's crumb tray does not work.
When repairing a toaster, make sure the unit is not plugged into anything, since repairing electrical appliances carries a risk of electrical shock. The risk is especially high for toasters, since they use electromagnetic resistance through metal to generate heat.
The internal thermostat in a toaster tells the solenoid how long to heat the food. If the thermostat is not interacting with the solenoid, you need to recalibrate the thermostat to get it working again. Make sure the toaster chassis is removed, and then locate the thermostat calibration screw or knob. Tighten or loosen this knob in order to adjust the toaster's heating cycle back to the desired levels.
The solenoid and the corresponding switch need to be replaced if they are faulty. Check these components by opening the chassis to examine the area around the thermostat or by removing the crumb tray to view behind it. If these components are not functioning correctly, the toaster will burn or fail to cook any food.