INVESTMENT FIRM RAISES CERTRON <CRTN> STAKE Louart Corp, a Los Angeles investment firm, said it raised its stake in Certron Corp to 237,000 shares, or 7.8 pct of the total outstanding common stock, from 164,000 shares, or 5.4 pct. In a filing with the Securities and Exchange Commission, Louart said it bought 73,000 Certron shares between Sept 9 and March 6 at a total of 109,315 dlrs a share. It said its dealings in Certron were for investment only, but said it might increase its stake. It said it has no plans to seek control of the company.