Hi norflo, swollen parotid which does not have a mass or lesion and which is nontender and does not show any sign of inflammation could not be due to a blocked duct but could be because of other conditions of which most common ones are seen in diabetes
chronic alcoholics, sjogeren syndrom (dryness of eye and dryness of mouthe will be experienced,) smoking
etc, if you have any of these habits quit them, then get yourself investigated for diabetes and for sjogrens syndrome. You could also get a FNAC done to get to the cause of it. Treatment will be depending on the cause and so it would be worthwhile to get to the root of the problem. Take the help of your general physician who would be your best guide.