http://fiche.ronayers.com/Index.cfm/...BAR_TOP_BRIDGE
That link might help it has a photo of all the parts involved.
More than likely the insert broke about a inch in if its spins. The bar end and the insert should have half circles that interlock so you can hold the bar end to keep the insert from spining. Lots of times the bar end breaks and takes about 3/4 of a inch of the insert with it. You would need to replace the insert also.
If you need to replace the insert a slide hammer works nice to remove it. There is a one way clip that snaps into a hole in the bar and is damaged when removed.