Interesting! I didn't know about that. Here's the patent on the concept:
That was an interesting read. Apparently antenna rattle is / was an age old problem!
Unfortunately I didn't take any pics of the internal grease (who knew that might be of interest?), but I did snap a pic of my repair process. My antenna had been snapped off just above the internal connection "nubbin". So I cut off the crimped section of the mast and peeled the remains of the mast tube off of the base. Cleaned up the mating surfaces a bit, then simply pushed the mast down onto the base again.
Bottom mast section is probably 2-3" shorter now, but the rest of it appears original - for better or for worse! Eventually I'll replace it with a repro or nice original, but for now there are other bugetary requirements :-)