When was the last time the public was allowed to climb up the Statue of Liberty's arm into her torch?

The torch was closed to tourists in 1916, following the Black Tom explosion (an act of German sabotage on a nearby island's munitions store that caused $100,000 damage to the Statue of Liberty).

https://en.wikipedia.org/wiki/Statue_of_Liberty

https://en.wikipedia.org/wiki/Black_Tom_explosion

The observation deck on the twenty nine foot torch was closed to the public July 30, 1916. World War 1 was raging in Europe and earlier that day German agents had attacked a nearby nearby waterfront munitions depot. The resulting explosion caused the equivalent of two million dollars damage to the statue. Lady Liberty was never designed to have large numbers of visitors. Her interior was a fire hazard and there was no emergency exit other than a single steep, vertigo inducing staircase.

http://www.time.com/time/nation/article/0,8599,1897552,00.html

Sometime in 1916, no exact date yet.
"Also in 1916, the Black Tom explosion caused $100,000 worth of damage ($1.98 million in 2008 dollars[32]) to the statue, embedding fragmentation and eventually leading to the closing of the torch to visitors. ... The ladder to the torch still is closed and has been since 1916."

https://en.wikipedia.org/wiki/Statue_of_Liberty

The Black Tom explosion occurred on July 30, 1916, so the closing was sometime after that.

https://en.wikipedia.org/wiki/Black_Tom_explosion

I've found a number of sites that say the arm was closed immediately after the Black Tom explosion, but the Straight Dope says that story is untrue and that the real reason was because a reworking of the torch allowed water corrosion.

http://www.jerseycityonline.com/stories/black_tom_island_story_eighty.htm

http://www.straightdope.com/columns/read/612/could-visitors-once-go-into-the-statue-of-libertys-arm

I can't find any information on this question with the US Park Service.

The first [closure] was in 1916 when German saboteurs blew up an arms depot near the New Jersey shore, just west of the Statue. The explosion impact damaged Liberty's arm, weakening the structure to the point that all public access to the torch immediately ended.

http://www.nydailynews.com/news/crime/german-spies-blew-state-liberty-1916-article-1.2687925

That would mean the last time the public was allowed to climb up the Statue of Liberty's arm into her torch was July 30, 1916.