Just to clarify after my last post:
When I say that the three canonical faculties share the same level of fallibility / infallibility - and I say that the level is zero --- that is a reference to the fact that "Fallibility" and "infallibility" are terms that refer to conclusions: to ideas that are reached after a process of thinking and coming to an opinion. Fallibility and infallibility are terms generally used to refer to whether a set of opinions is correct or incorrect when compared with the "Truth" (which is another abstract conclusion or concept).
I think most of us are agreed that the three canonical faculties do not provide "opinions" or 'concepts" or "conclusions" at all: therefore it is not proper to consider them to be either fallible or infallible. The faculties don't represent to you that they are handing you completed idea. Instead, they are handing you raw data (sounds, sights, feelings of touch, pleasure, pain, etc.) that are neither "right" nor "wrong." They simply are what they are, and from them we have to take what they give us and reach any opinions or conclusions that we want to reach.
I think probably I am preaching to choir in writing this but I wanted to clarify in case any "newer" readers happened on my statement and were wondering how to interpret it.