While fans lined up to see Star Wars Episode III: Revenge Of The Sith, one C-3PO was in the shop.

The incessantly chatty robot star of circa 1983 The Return of the Jedi, received first aid from Mary Coughlin, a graduate student in the Winterthur/ University of Delaware Program in Art Conservation, who interned at the Smithsonian Institution.

The golden robot was handled by the Objects Conservation Lab at the National Museum of American History. The diagnosis: An internal support added to him in the mid-80s was deteriorating and his gold coating was beginning to wear off after his many brushes with the Rebel Alliance.

The prognosis looks good. C-3PO has an advantage his human co-stars don’t: This patient’s parts are interchangeable.

“I have been in contact with people from Lucas Films and Industrial Light and Magic who have been very helpful in sharing with me how the costumes were manufactured, what could have caused some of the changes in appearance, and how other C-3PO costumes are aging with time,’’ Coughlin says. “They were even nice enough to send me an autograph from Anthony Daniels, the actor who played C-3PO.”

The bumbling C-3PO wasn’t Coughlin’s only famous subject—she worked on F.D.R.’s leg braces, Mr. Spock’s ears, a World War II bazooka and salsa singer Celia Cruz’s shoes.

She worked on a Civil War canteen, a lifebelt used on D-Day, Col. John Mosby’s crutches, a World War II rivet gun and the iron cladding from the C.S.S. Virginia. She helped clean the first iron lung.

The rivet gun and the life belt, now displayed in the museum’s “The Price of Freedom: Americans at War” exhibit, had a personal history dear to Coughlin.

“Working on all the World War II objects was very emotional,’’ she says. “It did make all the struggles, sacrifices and fears of that time period more real. My grandfather was a Navy doctor in World War II, so I imagine that he either was issued a lifebelt or was at least familiar with them. My grandmother was a ‘Rosie the Riveter,’ helping to manufacture airplanes during the war. It was a tangible link to the past.”

She says she worked on some objects she never would have expected when she began her studies—like the World War II bazooka and two prototype rockets. “When I got into conservation, I just never thought that one day I would work on a bazooka!’’ she says.

Coughlin, who will earn her master’s degree in August, says her experience has reinforced her belief that history is worth saving.

“The objects you see on display in museums are tangible links to our past. They give insights into our society as it has developed with time. If we lose those links, we run the risk of forgetting how we got to where we are now,’’ she says.

—Kathy Canavan