Here’s Mark 2:14:
And as he passed by, he saw Levi the son of Alphæus sitting at the receipt of custom, and said unto him, Follow me. And he arose and followed him.
And here’s the JST for that verse, with the change underlined:
And as he passed by, he saw Levi the son of Alphæus sitting at the place where they receive tribute, as was customary in those days, and said unto him, Follow me. And he arose and followed him.
(Note that this JST is not included in LDS Bibles. Not all of them are.) The JST removes the phrase “receipt of custom” and replaces it with “place where they receive tribute, as was customary in those days.”
I’ve noticed that most LDS operate under the impression that the JST fixes changes that have been made over the years to the text and thus restores it to what it originally said. I think some JSTs do that, but not all. Maybe not even most. This is an example of a JST that does not, I think, restore the text to what it said originally. I say that for three reasons: first, Mark would not have referred to Jesus’ lifetime as “in those days,” as if it were in the distant past. Secondly, Mark would not have felt the need to explain what a “receipt of custom” (modern English: toll booth or tax office) was–his audience would have known all too well what it was. And third, it is nearly impossible for me to imagine the circumstances under which a scribe would have changed the phrase “place where they . . . in those days” to “receipt of custom.” There is no theological, literary, logical, or other possible motive to make that change.
I think this is a pretty clear case where the JST changes the text in order to make it more understandable for the modern-day (in Joseph Smith’s time) audience. I’m certainly not the first one to notice that many JSTs are better understood as making the text more reader-friendly than as restoring a corrupted text, but I don’t think that that message is getting out of the LDS academic world and into the pews.
(As a side note, I’m actually fairly amazed at the number of JST changes that make the text easier to read–there is a lot of changing “saith” to “said” and that sort of thing. It makes me think that Joseph Smith thought that it was important that the text be as easy to read as possible for the average person. Which, in turn, makes me wonder what he’d think about our continued use of the KJV, but that’s a topic for another post.)