Vanguard Equity Income Fund trustees hired Wellington to replace Spare, Kaplan, Bischel as one of the funds three subadvisers. The amount of the mandate was not provided by Vanguard officials. The change was made to fine-tune the funds investment management mix and was not performance-related, said John S. Woerth, a company spokesman. Wellington will use a more fundamental approach than Spare, Kaplan, focusing on stocks with reasonable yields and the possibility of growing dividends. Spare, Kaplans approach was too similar to that used by another of the funds subadvisers, Newell Associates, Mr. Woerth said. John A. Levin remains the funds third subadviser.