Hi Bill,
Is the rubber frozen in the chassis hole preventing the bolt from being extracted?
If so then the chassis hole probably rusted and has expanded and locked the rubber in place. I had that happen and I used a torch on the bolt to soften the rubbers grip and extract the bolt then I was able to use a round ceramic tile cutting blade and cut through the rubbers to eventually free that up through a series of thin blade screw driver wedges.
Mike