The Janome overlocker is working again—the upper looper was way out of place (not sure how that could happen unless force was used). Also, the needles in the overlocker should be the same type, not mismatched.
The Necchi DF4 Millepunti Professional Overlocker is still not working. One of the needles in the needle plate was bent; I straightened it, but it’s still not functioning properly.@textilestechs