I believe it was in 1932 that the Society changed its position regarding the Jews. Rutherford was then in the process of writing a three-volume series, Vindication, on the book of Ezekiel, and when he came to the restoration prophesies he applied them spiritually to the anointed remnant rather than a return of the Jews to Palestine.
This is actually the classical belief known as replacement theology - that the new Christian Israel replaces the old natural Israel as God's chosen people. The only difference is that the Society limits the new Israel to its own anointed members instead teaching that it refers to the Christian church at large.
Russell had actually embraced a newer theology known as dispensationalism - the belief that God's purpose is being worked out in a series of dispensations or ages in which his dealings with mankind are somewhat different in each. So, according to this belief, the Jews have temporarily lost divine favor during the Christian or Gospel Age, but are expected to be restored during the Millennium.
Even newer is the thought which is becoming more widespread today, that the Jews and Christians each have their own covenant with God, and that these covenants are operating simultaneously.