Diagnosis
The motor is overheating. The most common cause is a worn or slipping drive coupling. This is the plastic piece that connects the motor shaft to the blade assembly.
How to Fix It
Unplug the unit. Remove the blender jar. Look inside the drive socket on the base. You'll see a black plastic star-shaped coupling. If it's cracked, melted, or the teeth are worn down, it must be replaced. Part number is usually BFP-703-CPL. Order the official part.
If That Didn't Work
The motor bearings are seizing. This is a terminal failure. You'll hear a loud grinding or screeching with the smell. The entire motor assembly needs replacement. Contact Cuisinart support.
Heads Up
Stop using it immediately. A slipping coupling creates excess friction and heat. Continued use can damage the motor windings permanently.