So I never had smoke ever coming from a blender but my knowledge in general seeing $@$* happen to blenders can answer your question. Those black flakes are the flakes from the bottom or the attachment for the blade. Through years those gears are always rubbing against each other and eventually fall apart creating the flakes. If I am right the smoke is from the gears rubbing at high speeds as the motor continues to spin as the blender blades and gears are stuck in one position. This friction is enough to burn, melt, and to create smoke. If the gears on the blades used to latch onto the motor looked all gibled and weird looking. That might be your problem and you just need to buy new attachments. If not then your blender is not good and needs to replaced.