The Rambam's eighth Principle of Jewish Faith states that the entire Torah in our possession - every verse - was dictated to Mosheh Rabbenu and that it has not changed.
However, we have explicit passages in Hazal that tell us that the Torah had to be critically reconstructed from a multiplicity of scrolls, each with slightly different wording in certain passages (cf. y.Ta`anith 4:2) and that these were apparently used by Ezra HaSofer in his reconstruction (cf. Avoth De-Rabi Nathan 30b).
Additionally, we have an explicit text in the Gemara that says that the Amoraim were not experts in defective and plenary spellings in the words of the Torah (cf. b.Qidhushin 30a).
And in the Rambam's own day there were multiple versions of the Torah (differing only in a very few, slight ways), including the mesorah of Yemen which differs from Ashkenazi and Sefaradi mesorah in five places!
Not to mention the accurate placement of petuhoth and setumoth, which has enough halakhic weight to pasul a sefer Torah if made incorrectly.
My question is:
Surely the Rambam knew these passages from Hazal and the facts on the ground, so how could he write such a seemingly dogmatic statement regarding the Torah "in our possession"? Are we missing something? Was he?
NOTE: I am aware of the simplistic and non-Maimonidean wording of the popular "Ani Ma'amin" on this principle of faith and I reject it as not accurately representing the intent of the Rambam in his fuller, more original wording of the eighth principle.