We can deduce some things about the so-called Nazi Bell from its shape. It's circular and very squat. This suggests it might contain a rotating apparatus with a vertical axis. Perhaps a spinning electromechanical system. But how could that be electrogravitic? After all, we do not see any antigrav effects in spinning massive generators. Possibly it used high frequency currents playing in strange ways with electrons. And that brings to mind Tesla, who was active in that same general era. Hmm. Why did the government confiscate all his papers after his death? Hmm.

The so-called 'red mercury' probably was some kind of electron-dense metal in liquid form, able to be spun or to rotate but have properties that solid metal doesn't have due to its crystalline nature (although solid metal isn't really a crystal). My guess is any electrogravitic effects came from the sheer density of electrons. Maybe providing a shield against gravity. Normally we do not have any way to accumulate a huge number of electrons together in a space because isolated electrons will repel each other. But maybe the Nazi physicists conceived of a way to use electron-dense atoms and exploit the particles outside the nucleus - the electrons - in some way that interacts with gravity,