I'm trying to replace the antenna mast on my Accord. I'm pretty sure the motor works, since when the antenna attempts to go up I hear clicking. I ordered a replacement mast.
The problem I have right now is that the silver nut that holds the antenna in is missing. It looks like whoever tried to do this last time ripped it off.
Since that silver nut is missing, I'm not really sure how to get it off. Does anybody have any ideas?

 

Its hard to tell from the picture, but it looks like the threaded part is still there.

You may want to try a punch on the metalic part of the remaining nut in your pic. If not, you may have to use a dremel to cut the black plastic part off then use a vice grip to remove the completely exposed threaded part of that nut.