I have been there many times.
I used to live in the neighborhood directly behind it.
I was on leave from the Army when he died and saw all the activity at the Library for the ceremony.
I also remember as a kid seeing the glow of the Secret Service surveillance monitors of the house across the street from his home.
When the National Park Service took over the Truman home I got the full tour of the entire house. This included all of the areas not included in the official tours.
I was a Police officer then and a bomb threat was called in. We were searching to see if there was a bomb!