SALEM ?? A Swampscott man charged twenty years ago with raping a child is trying to have his file sealed in Superior Court.William J. Harrington, 55, of 37 Jessie St., was accused in 1988 of twice raping a 5-year-old child in his home, but the case was dismissed in April of 1989 by Superior Court Judge Robert K. Mulkern after a jury was impaneled in Newburyport to sit and decide his case.The court papers, however, do no stipulate the reason for the dismissal of the charges against Harrington.Attorney Russell Sobelman appeared Friday in Salem Superior Court asking Judge David A. Lowy to seal his record, saying that Harrington, is trying to become a Level 6 mutual fund broker and doesn?t want his record public.He explained that Harrington has not been in any trouble for years, the case was dismissed and there was no probationary period for Harrington.Lowy was reluctant at first to seal the file, saying there are first amendment issues involved.After reviewing law material, Lowy told Sobelman he will have to file additional materials including a motion and affidavit with the court before any decision can be made, which Sobelman said he would do.