Nikon Super CoolScan 4000 ED User Manual page 85

Problem
The end of the film is folded.
The end of the film is tapered.
Care should be taken not to injure yourself when using scissors to trim the film.
Film that has been repaired or that has just been developed may jam in the adapter. If the film jams, use
the FH-3 film holder with the MA-20 (S) slide-mount adapter.
Solution
Trim the folded portion from the film, cutting the
film straight across and being careful not to cut
across the perforations.
Trim the end of film straight across, being careful
not to cut across the perforations.
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