Diagnosis
Creating nut butter is the highest stress task for this blender. The burning smell indicates potential motor brush or winding damage from sustained overload.
How to Fix It
For nut butter, you must use the specific 'Batters' programmed cycle. Do not attempt to blend nuts on a manual high-speed setting. The 'Batters' cycle uses intermittent power to manage heat. Use a maximum of 2 cups of nuts per batch.
If That Didn't Work
Persistent loss of power and odor requires service. This is a sign of worn motor brushes or damaged armature windings. Contact Blendtec support; this may be a warranty issue if the 'Batters' cycle was used correctly.
Heads Up
Making more than two consecutive batches of nut butter without a 10-minute cooldown period between them will void the motor warranty due to operator misuse.