Recliner position lock stuck
You may very well be right that the wear in the lock position notches is leading to the problem. With as much wear and metal deformation showing one has to wonder if the spring loaded pin is also worn severely. 

One possible fix for this is to file away the metal some where the wear in the lock notch has produced an undercut. You would have to be really careful to not file away too much or create a condition where the pin would not stay in the notch as intended.

If the pin itself is worn it would need replacement as it appears to be a specialty design with the spring hook up. Although a replacement could be made if access to a metal turning lathe and tooling was possible.