What was found
AFTER TAKEOFF, THE LANDING GEAR WAS SELECTED UP, THE A AND B DOWN PROXIMITY LIGHTS REMAINED LIT, AS WELL AS ALL A AND B DISAGREEMENT LIGHT. AFTER TWO MINUTES, GEAR CAME UP. CYCLED TWO TIMES WITH SAME RESULT. RETURNED TO SFO. REPLACED LANDING GEAR CONTROL BOX. CYCLED THE GEARS SEVERAL TIMES. OPS CHECKS GOOD. P/N ON: 120-38594-501, S/N: 120009R, S/N OFF: 120081R.