What was found
AFTER SELECTING GEAR UP, ALL RED AND GREEN INDICATING LIGHTS REMAINED ILLUMINATED. FOLLOWED QRH AND RECYCLED LANDING GEAR WITH SAME RESULTS. RETURNED FOR LANDING. REMOVED AND REPLACED LANDING GEAR SOLENOID VALVE. REMOVED AND REPLACED LANDING GEAR CONTROL BOX. CYCLED GEAR 5 TIMES. OPS CHECK GOOD, BOTH CONTROLLER AND SOLENOID VALVE. OPS CHECK GOOD IAW MM 32-32-03. LEAK CHECK GOOD. BOX P/N: 120-38594-501, S/N ON: 120349, S/N OFF: 240191-310. VALVE: 18190-003, S/N ON: 343, S/N OFF: 486.