Smoke is a byproduct of roasting coffee. The darker the roast, the greater the column of smoke. The volume and aroma of the smoke are both indicators of the roast level. But the smoke carries with it oils. Wherever the some is being emitted from the roaster you can be sure that over time there will be baked-on deposits.

  One no   area of this buildup is on and around the bean loading chute cover The emission of smoke there is normal for the roaster to do that, and it does not indicate a problem with the main fan.

   To lessen the burnt-on residue, what I recommend that when the roaster has completely cooled, use a soft rag and a cleaning product to clean the area on the top cover of the machine around the opening, the cute cover, and the loading chute itself of the oily buildup the smoke deposits. I use Simple Green and the yellow microfiber rags from Costco (I have them all over the house!). But any such combination of rag and similar product will work.

   In terms of the main fan, if the blades are getting a buildup of coffee-related particulate matter and oils, you can remove to main fan from the roaster, remove it from its mounting frame, and then clean the blades with a toothbrush and the Simple Green. Keeping the blades clean maintains its efficiency. Before removing the fan from the frame, take note of its orientation!
   Here is another tip. There is a product called "303 Aerospace Protectant" which is sort of like Armor-All but has no silicone which is terrible on vinyl. Use it on the external plastic parts of the roaster. I use it when restoring Hottops and they look new afterwards. Great for automotive plastics, vinyls, and tires and such as well. I buy it by the gallon for home use!