During the 1974 Watergate hearings, then-Chief of Staff Alexander Haig blamed a famous, 18 1/2-minute gap in President Nixon's tapes on "sinister forces." But a newly-released memo shows that the White House tried to blame Rosemary Woods, Nixon's loyal personal secretary, who had claimed to have erased just a small part of the tape accidentally. The memo, written by Woods' attorney and made public today by the National Archives as part of a cache of more than 35,000 Woods documents, states that White House lawyers Leonard Garment and Fred Buzhardt told U.S. Judge John Sirica that Miss Woods intentionally erased the tape. Garment today denied the episode. Woods, now 77, hasn't commented.