What was found
WX RADAR NOT DEPICTING ANY RETURNS WITH VISUAL CONFIRMATION OF THUNDERSTORMS IN THE AREA. GROUNDED - YES. REMOVED, REPLACED WEATHER RADAR DRIVE UNIT, OPS CHECKS GOOD IAW B737-9 AMM 34-41-11-000-803, 34-41-11-000-804, 34-41-11-400-804, 34-41-00-710-801.