So, as Father Cekada has said, most SVs have abandoned the position that Roncalli, Montini, et al. had "fallen" from the papacy, but instead believe that they were never popes to begin with.
What is the evidence that Roncalli and Montini were manifest heretics before their respective "elections"?
Roncalli was a Cardinal in good standing and Montini an Archbishop in good standing under Pius XII. Sure, Roncalli was "suspect" of Modernism, but that suspicion was not enough to prevent him from being made a Cardinal by Pius XII.