The modern consensus that the “Long” text of Tobit is earlier than the “Short” has brought about a paralysis in attempts to restore the Greek, with the very unsatisfactory text in Sinaiticus coming to serve as our de facto best effort. It is important to appreciate that the Long witnesses do not constitute a specific and coherent recension, capable of reconstruction in its own right, but are potentially miscellaneous texts, that happened individually to elude the two major revisions of the tradition. Original readings are preserved in both the revised and unrevised witnesses, and if we are to progress then we need to employ and evaluate all those witnesses. The paper ends with an attempt to reconstruct the original form of 4:7-19, which is lacking in Sinaiticus, as an illustration of the scope for such progress.
Weeks, S. (2013). Restoring the Greek Tobit. Journal for the Study of Judaism: In the Persian, Hellenistic and Roman Period, 44(1), 1-15. https://doi.org/10.1163/15700631-12340377