Can we see more photos of the site?
Additionally, Chris luleys book on wood decay fungi, or his website:
https://www.treerot.com/
will help identify if the fungus is parasitic or not.
I agree with the sentiment of crown reducing, if possible and safe, based on the limited context of the...
Also, not sure with your specific model, but check for snap rings. They sometimes rot off or are recessed really well. May not apply here but easy to check for.
A bushing press, u joint press, heat, wax, Milwaukee impact.
I've made my own cups and adapters for different applications. Lube the threads and wear safety glasses...