It looks like the outer 1/8" of hex has been rounded off. Have you actually pushed (or hammered) an allen wrench at least 1/2" in to make sure there isn't still engagement? I'd try that first.
If you have an opening on the DS, you can try using a long shaft allen from that side going into the back of the NDS allen bolt.
Last edited by Kontact; 04-20-24 at 05:41 PM.