Gophers? Look for tunnels. I found one tunnel entrance that ended under a large pot. Maybe he could smell roots and wanted what was in the pot. What was the plant? A Cordyline I had re- rooted because a year earlier a gopher had eaten all the roots to that 7' and old Ti plant. Cats caught him.

I'd do a diagnosis of sorts and sacrifice that obviously-ready-to-remove one, cutting into the core to see if there's rot / invasion of some sort. I know a plant fellow in Berkeley who I can send the link to this question too - he'd have useful information and has been a contributor here, though we've missed him lately. Editied to add - the plant fairy already made the 'can' into the 'did' happen.

If the main stem is damaged beyond redemption maybe try cutting it off with a sterile knife till good healthy tissue is reached, often attenuatas will regenerate from the base and throw out new pups. My regular green one developed a unhealthy top after cold damage last year, I’ve cut it off and now have several pups growing happily from the severed base. It lives in an unheated greenhouse here in the U.K. with temps as low as -8C so far and the only extra protection is from a thin horticultural fleece thrown over it and all my other plants in there. Gill

@stanofh 10a Hayward,Ca S.F. bay area I was playing with the idea of putting a single Firesticks in the center of the mound, where it could grow to be a center point of focus, then plant nothing but Agave attenuata Foxtail around the perimeter of that. I really worry about the Firesticks rotting out in clay soil, so I would probably make the mound out of sandy loam and add maybe 10% garden waste compost to that so that it has at least some water retention and nutrition.