What was found
LANDING GEAR RETRACTION DURING TAKEOFF, RT MAIN GREEN DOWN LIGHT REMAINED ILLUMINATED (UNLOCK LIGHT NOT ILLUMINATED) PERFORMED LANDING GEAR WILL NOT EXTEND CHECKLIST AND BLEW GEAR DOWN WITH NITROGEN SYSTEM. REMOVED RT MAIN GEAR ACTUATOR DUE TO HIGH RESISTANCE IN DOWNLOCK SWITCH. INSTALLED RENTAL ACTUATOR IAW CE560XL M/M CH 32-30-04, OPS CHECKED GOOD IAW CE560XL M/M CH 32-01-00. DURING GEAR SWING AND BLOW DOWN ACTUATOR (RENTAL) WAS INSPECTED AND RETURNED TO SERVICE BY CESSNA AIRCRAFT CO CRS CN1R918C.