Hitachi DA4 MX423: Cassette carriage binding?

[Benjamin3000]

It's getting stuck at about the midway position. Even if the cassette carriage is unscrewed and removed from the rest of the movement, and I nurse it through it's cycle, I can feel it sticking/binding in the same spot. Nothing appears bent or cracked.

Does anyone have inside pictures of this model, so that I can figure out how the gears "should" be?

I never saw it in full working condition so I didn't get the chance to make timing marks.