A common source of jumping out of gear on the XT, besides the usual worn or bent selector forks, is wear in the stopper lever arm's bearing (11 on the diagram below). Any slop in this lever will result in gears not quite engaging will eventually cause accelerated wear of the shift forks, making the problem worse. If it fails completely it can effectively cause two gears to engage at once with catastrophic results! This part seems to be a more common weakness on engines assembled in 2009.

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