What was found
FLT 1162 - MKE-SBN - CYCLED THE LANDING GEAR HANDLE, THE LANDING GEAR DID NOT RETRACT. THE CREW ATTEMPTED TO CYCLE THE LANDING GEAR A SECOND TIME, WITH NO RETRACTION OR ANNUNCIATION SHOWING GEAR RETRACTION THE CREW RETURNED TO MKE. UPON INSPECTION MAINTENANCE FOUND THE CONNECTOR CONTACTS AT THE GROUND SERVICE VALVE DIRTY. CLEANED AND LUBED THE CONTACTS, RETRACTION CHECKED GOOD ON JACKS. (M)