WASHINGTON (AFP) - Wishful thinking and three heel clicks whisked Dorothy back home in The Wizard of Oz, but it will take hard cash to restore her ruby red slippers.

In the 1939 classic film, Dorothy, played by Judy Garland, danced down the yellow brick road in the sparkling shoes. Now the Smithsonian's National Museum of American History - where they are on public display - has launched a Kickstarter crowdfunding campaign to raise US$300,000 (S$415,700) towards restoring their pizzazz.

The shoes, made nearly 80 years ago, are in dire need of repair as well as a new display case to protect them from environmental harm, the museum said.

The Smithsonian Institution - which oversees museums and research centres in and near Washington - receives federal funding to support its core operations, but the money will not cover the cost of repairing the shoes, it added.

It often solicits corporate and private donations to pay for projects beyond its budget.

Conservators say the sequins on the leather shoes are flaking, leaving them more of a washed-out auburn than the glittery ruby colour for which they are known.

The Smithsonian had raised just over US$85,000 as of Tuesday afternoon (Oct 18), with slightly under a month left in the fund-raising campaign.

The MGM Studio prop department created the low-heeled shoes by dying commercially manufactured low-heeled slippers red and attaching red sequined netting.

The slippers became one of the film's most iconic props, on near-constant display at the museum since they were anonymously donated in 1979.

Millions of visitors view them each year, and they are slated to be part of a 2018 exhibition on American innovation in music, sports and entertainment.

The Kickstarter campaign is the Smithsonian's second, after it raised US$719,779 last year through crowdfunding to conserve Neil Armstrong's spacesuit.

The museum issued its appeal with the words of the Wicked Witch of the West: "These things must be done delicately - or you hurt the spell."