The fourth section of the 25th amendment to the US constitution provides for the president to be declared unfit involuntarily. The first of its two paragraphs describes the declaration itself, made by the vice president along with "a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide."
The second paragraph describes a mechanism for the president to resume the "powers and duties" of the office by declaring "that no inability exists." This paragraph also establishes a mechanism for "the Vice President and a majority of either the principal officers of the executive department or of such other body as Congress may by law provide" to challenge the president's declaration.
This question is about the difference in the designation of those whose action is required along with the vice president. The first paragraph uses the word "departments," plural, and the second uses "department," singular.
I suppose that the second paragraph was added during the debates on the amendment, and that the use of the singular in the second paragraph is probably an error.
Would courts be likely conclude that the difference is unintentional? If not, does the use of the singular change the meaning of the phrase significantly?
I am especially interested in answers that look at the the legislative history of the amendment to support or refute the hypothesis that the second paragraph was an addition to the original form of the text. As far as I can tell, the relevant congressional documents are not available online for the 1960s.