I divided up Section 3 by each subject referred to and used clause #5, "who, having previously taken an oath", as the mid-point where the dependent clauses that follow refer back to the prior clauses.
There is a high level of parallelism/symmetry with the clause(s) but not a perfect correlation. For example, "elector of the President and Vice President" is explicit in the first half but not mentioned in the second. Perhaps because Electors used to come from the State Legislatures, therefore subject to #8?
This amendment poses more questions than answers. If someone tells you they know for sure what it means and how to interpret it, they are not being completely honest. My opinion: I dunno.
Is this clause “Self-Executing”? Does it require a finding by the Legislature/Congress (House and Senate)/Court (Supreme or other)? Is the President entitled to “Due Process” under this Section?
Are the President and VP subject to the terms of Section 3?
Is the President considered an “Officer” even though he occupies an “Office”? Here are a YES and a NO perspective on the issue. HERE is another view on the Legislative history.
Is including “electors of the President and VP” (for Electoral purposes) a check on the President and VP and naming them explicitly not necessary?
What were the debates around wording at the time of the writing of this section? Why was the President and VP not mentioned EXPLICITLY?
The wording is different in each oath. WHY? Note word "support" is not in the Presidential Oath. Some say this is significant.
Many questions, few solid answers...