CENTRAL PENNSYLVANIA <CPSA> BUYS STAKE IN FIRM Central Pennsylvania Savings Association said it made a 30 pct investment in <Pinnacle Mortgage Investment Co>. Terms were not disclosed. Pinnacle, incorporated in 1985, generates about 60 mln dlrs in closed mortgage loans annually. Central Pennsylvania also said its directors recently approved a letter of intent to acquire Hamilton-Reliance Savings Association of Norristown, Pa.