[Ron Ramirez]

Notice the lug on the bakelite block in question is grounded.

The wire ensures the rotor of the tuning condenser is properly grounded.

You may have to resort to desoldering braid to get that solder off, but you don't have to remove all of the solder - just enough to get your 1/4" socket wrench onto the bolt. One trick you can try: Heat the solder, then immediately put your socket wrench on the bolt. This may push enough of the solder out of the way so that you can get the socket on the bolt. Been there, done that...