Second-half drama featured a brace of goals by Gareth Smith before Corkin added to the visitors’ advantage.
Scott Richardson failed to find the net from the penalty spot and Crusaders hit back with late goals.
However, Rangers proved resolute to protect the slender lead until the final whistle.
“We have now won 11 on the bounce in the league,” said Tony Bell, the Rangers manager. “Quite a few other teams have games in hand but it is good to have points on the board.”
RECTORY RANGERS: Luke Bush, Wayne McClure, Philip Pedlow, Gareth Willis, Stephen Woods, Colin Corkin, Scott Richardson, Gareth Smith, Dean Geddis, Joel McConnell, Willie Duke. Subs: Ryan Donaldson, Alex Henry, Graeme Bunting.