jevpots

It's an electric fan under the burner port to boost the air flow to the burner. Speed is adjustable. Adds an extra dimension to the kiln controls. Turbofan is the name given to it by the manufacturer.

The relay (if its that which is buzzing) is in the box containing the Variac - that's the thing which is turned by that cog wheel. It'll be roughly under where that yellow strip is but on the inside of the box.

Yes, usually in the same box near the Variac

I find how you arrange the kiln shelves affects the heat circulation. Slightly overlapping bottom to top on the burner side and keeping the backs close to the back wall send to help me. I also have the model with the turbo fan which adds an extra dimension to circulation. I put thermocouples in the top and bottom bung holes to give me extra feedback too.

Maybe the switching relay?