When I was a teenager (over half a century ago), I once watched the local gas station owner (old time place that had a grease pit; no lift) heat a stubborn tie rod end on a truck with a torch to get it to take grease. As I recall, he just got it hot, but not hot enough to glow. Then he plugged on the grease gun and it took grease, but the grease melted. He went on to do something else, came back after it cooled and greased it again. It took grease normally then.

It would be a lot of trouble to do that on your roadster. You would have to remove the rubber and possibly take the rod end off. Try your idea first and if it doesn't work you can try heat as a last resort next winter.