What was found
CREW REPORTED, AFTER GEAR RETRACTION, AND DURING CLIMB CHECK LIST, RIGHT GEAR UNSAFE LIGHT REMAINED ILLUMINATED. AIRCRAFT RETURNED TO MKE. MAINTENANCE WAS UNABLE TO DUPLICATE PROBLEM. REMOVED AND REPLACED RIGHT MAIN GEAR UPLATCH SWITCH AS A PRECAUTIONARY. PERFORMED GEAR SWING IAW DOUGLAS MM. ALL FUNCTIONS NORMAL.