What was found
VCP/JFK - EN ROUTE AT FL 350 IN CRUISE, NR 1 ENGINE LOST POWER, N1, N2, EPR, AND FUEL FLOW DECREASED AND EGT INCREASED. RE-START ATTEMPTED, BUT WAS UNSUCCESSFUL. DESCENDED TO FL 310 AND WAS ABLE TO RE-START ENGINE USING GROUND START PROCEDURE. REST OF FLIGHT UNEVENTFUL. POST-FLIGHT BORESCOPE INSPECTION FOUND NO DISCREPANCIES. ADDITIONAL INSPECTION FOUND A LEAK AT A B-NUT ON THE PS4 LINE. TIGHTENED B-NUT. ENGINE RUN-UP PERFORMED IAW MM. ALL PARAMETERS NORMAL.