(1) Possession of an article on which an identification number is obscured is prima facie evidence that the person possessing it obscured the number with intent to hinder or prevent identification of the article, and that he knows that the identification number is obscured.

(2) A person is presumed to know an identification number on an article has been obscured if he has received other articles with obscured numbers within the year preceding the alteration offense charged.

(3) A person is presumed to know the identification number on an article has been obscured if he is found in possession of other property with obscured numbers.

(4) A dealer in secondhand merchandise who is found in possession of an article with an altered serial number shall be presumed to have failed to inspect the article for alterations.