A New York district judge appointed a new consultant yesterday to oversee the operations of First Jersey Securities Inc.

The consultant, Benjamin L. Lubin, was named as a condition of the consent decree signed by the brokerage firm last November after a 10-year feud with the Securities and Exchange Commission. The agency had charged First Jersey and its president, Robert E. Brennan, with manipulating the price of Geosearch, a stock it was also selling to the public.

Lubin is the second overseer to be named by Judge Milton Pollack. Alan R. Bromberg resigned in December after questions were raised about a possible conflict of interest. Bromberg, whose name had been suggested by Brennan, had been working on a series of books on securities law with First Jersey attorney Louis D. Lowenfels.

Lubin, a financial consultant who specializes in securities operations for banks, brokers and insurance companies, will review the existing sales practices, business operations and supervisory procedures of First Jersey Securities to ensure that everything is in compliance with securities laws. He has 90 days to recommend new or revised sales practices if his review of the company's operations discloses compliance problems. If First Jersey objects to a particular recommendation, the judge will decide whether it must be followed. The firm would have a year to carry out the recommendations.

Six months after it notifies the court that the recommendations have been put into effect, Lubin will again review First Jersey's operations.

The appointment of a consultant is a very rare event, according to an SEC spokesman. It resulted from a consent agreement First Jersey signed without admitting or denying the charges.