What was found
STL - FLT 687 - AFTER TAKEOFF, GEAR HANDLE RAISED, RED GEAR UNSAFE LIGHTS REMAINED ILLUMINATED. CYCLED GEAR. RED LIGHTS REMAINED ON FOR 3 TO 4 MINUTES THEN WENT OUT. HYDRAULIC PRESSURE 3000 PSI. REPLACED LANDING GEAR WARNING LIGHT SWITCH, MFG P/N V3-601. (M)