My 2015 Honda Accord EX-L V6 was leaking transmission fluid.
After inspecting it, I saw that some fluid was leaking under Cap Assembly A (Part 3 on the reference pic*).

So I'm sure I found the source of where the leak is, questions are the following.

Which of the following might be the problem?
-Could it be the just the O-Ring (Part 25*), Ball Bearing (Part 18*), or the Snap Ring (Part 16*)?
Would removing the cap and looking at the parts above mess up anything?
Would this be an easy fix or should i just take it to a mechanic?

Thank you!!

*Last pic as reference