Does anyone know how to swap the com ports on an Ad-40 voice mail system?

I have an NEC2400 PBX that is connected to an AD-40 Voice mail system....I know that com port one is bad and I want to switch it to Com port 2 so that I can get message waiting lights working again. I have digital line cards that are taking care of the integration...The com port is only used to control message waiting lights