i think that the bar has an internal tapped hole for the bar end, remove the other side and verify.
if the tapped hole is ok, then just replace and use loctite.
if the hole is stripped then it's choice time.
1. new OEM bars $190.00
2. new universal bars $60.00
3. several counter weight options on anamzon/ebay/dennis-kirk/ etc...
you can use bark-buster mounts in the bar end to re-attach the weight.