The Thomas Carnival general manager declined Thursday to identify the cause of a malfunction on the Zipper ride at MontanaFair in Billings earlier this week, calling it a "moderate severity concern."Fair officials confirmed a ti re did come off the Zipper on Tuesday night. Video was captured and shared on social media of the ride being stopped with riders still on board.Thomas Carnival General Manager Chris Atkins said those riders were safely evacuated and no one was injured.Previous MTN story: Tire flies off Zipper ride at MontanaFair, prompting evacuationAtkins said many Thomas Carnival rides are decades old. The merry-go-round dates back to 1956. The Zipper, built in 2001, is actually one of the newer rides. The newest ride at this year's fair is the Casino, built this year.Atkins said rides are refurbished at a factory in Minnesota when needed, noting most new rides on the market today come from Europe.Related: Tire flies off Zipper ride at MontanaFair, prompting ride evacuation ...read more read less