A brother I used to know was df'ed for something back in the 50's, that in the 60's changed, but the df'ing congregation would not reinstate him. In the 70's, he packed and went to Brooklyn, and came back, with a letter, saying to treat him as if he had never been df'ed in the first place. That the original issue had been a oversight on the wt's part dealing with reasons to be df'ed back in the 50's.
Dwain