Water Distiller Output

I have a Waterwise 9000 distiller. Lately I noticed that the output has fallen off. I distilled 1 gallon yesterday and measured the output. I had a little less than 3 quarts.
A little water does leak out around the fitting that connects the kettle to the distilling coils. The water that leaks out is far less than one quart. Could the remainder of the loss come from steam loss?

Is this normal? If not, is there any way to fix it?