JUST five days after reopening, the Melbourne Star Observation Wheel has spun into trouble.

The 120m-high giant observation wheel in Docklands was shut down temporarily on Saturday after a technical issue forced customers to get off midway through a ride.

A passenger, who asked not to be named, said she was on the wheel with her younger sister about 3.30pm when it "just stopped turning".

She said the wheel had been stopping to let people on and off but when it remained still, passengers were told there was a problem.

"The turning mechanism just stopped working and the cabin was rocking," she said.

"It was a bit scary but they spoke to us constantly and told us to stand round the edges to help distribute the weight."

Melbourne Star Management Group spokeswoman Sally Abbott said an "isolated incident" had been found by the technical crew and customers had to disembark the wheel to allow for a full inspection.

She would not reveal the specifics of the problem.

Ms Abbott said no staff or guests had been in danger.

She said all guests had been kept informed through the in-cabin communication system.

"All guests were attended to on their disembarkation by our staff to ensure they were all fine, extended full refunds and return passes, which the majority of guests accepted while being offered refreshments," Ms Abbott said.

She said operation continued after a 15-minute delay.

The wheel, originally known as the Southern Star Observation Wheel, was open for 40 days before closing in February 2009 because of cracks caused by extreme heat.