Sorry, TheOldHippie, but I never saw Rutherford's later books as barely coherent rants. His speeches became increasingly disjointed and tangential, but the books were obviously not the works of a drunken old sot living out his days in the luxurious environs intended for the Ancient Worthies. The defenses in known early Franz pubs are quite like the defenses in the "Rutherford" work Riches, for instance (1936). Franz' later works just showed more refinement of phrasing, but the construction of argumentation is nearly identical.
As for the teachings of Rutherford being done away with, aside from those surrounding 1925 I can't imagine what teachings you are referring to. Doctrinally, there is little changed in the primary teachings from 1940 until now. All the key dates that were recognized then are still recognized now, the authority structure as presented then is identical to the one JWs teach now—with some modifications to titles in congregational authority, the other sheep were already classed as separate from the little flock, the little flock was already being identified as the channel, the Society had not yet taken the name Governing Body, but the concept was in full force and had been for a few decades. I don't know which to teachings you are referring. The vaccination ban was already in place, providing the basis for the later ban on blood transfusions.
Also, the early works of Rutherford were bombastic and charismatic in a style that matched his public speaking style. Those attributed to him from about 1934 forward show a decidedly muted tone and an increased dependence on strength of argument and persuasion, rather than on repeated emphatic assertion—a primary characteristic of Rutherford's communication style until his death.
The teachings of Russell were done away with. Almost entirely. But that was not true of Rutherford's (Franz') teachings. They survive to us nearly intact, save changes to prophetic fulfillments that failed to materialize as planned. Doctrines were added or tweaked, but few of Rutherford's (Franz') teachings were discarded.
Respectfully,
AuldSoul