In October 1964, the U.S. Government Printing Office released 26 volumes of testimony and evidence compiled by the Warren Commission. Volume 18 of the commission's hearings reproduced 158 frames of the Zapruder film in black and white. However, frames 208–211 were missing, a splice was visible in frames 207 and 212, frames 314 and 315 were switched, and frame 284 was a repeat of 283.[8] In reply to an inquiry, the FBI's J. Edgar Hoover wrote in 1965 that 314 and 315 were switched due to a printing error, and that the error did not exist in the original Warren Commission exhibits. In early 1967, Life released a statement that four frames of the camera original (208–211) had been accidentally destroyed, and the adjacent frames damaged, by a Life photo lab technician on November 23, 1963.
Life released the missing frames from the first-generation copy it had received from Zapruder with the original.[9] (Of the Zapruder frames outside the section used in the commission's exhibits, frames 155–157 and 341 were also damaged and spliced out of the camera original, but are present in the first-generation copies.)
http://en.wikipedia.org/wiki/Zapruder_film