What was found
AFTER TAKEOFF AND GEAR RETRACTION SELECTED, THE 3 GREEN LIGHT EXTINGUSHED, BUT THE RED LIGHT REMAINED ILLUMINATED. CLIMBED TO 6000FT ON THE AUTOPILOT. AFTER 3, 90 DEGREE TURNS ON THE AUTOPILOT WE FELT A HARD BUMP FROM THE UNDERSIDE OF THE AIRPLANE AND THEN THE RED LIGHT EXTINGISHED. RE-ENTERED THE TRAFFIC PATTERN AN MADE A NORMAL LANDING WITH NORMAL INDICATIONS. FOUND RT GEAR UPLOCK SWITCH RESISTANCE HIGH. R & R SWITCH WITH NEW UNIT. JACKED ACFT AND PERFORMED LANDING GEAR OPS CHECKED. ALL CHEKS NORMAL IAW MM 32-10-00, 32-00-00.