I have my MPE with Server Type as 'ADDITIONAL POLLER' and I need it to be changed to 'MAIN POLLER'. Are there any documentation that I can follow on how to apply this change?
This article details the registry keys were this information is stored. Make sure to follow steps, backup everything (DB and registry) before modifying anything.
I would also check that the "InstallType" is "MainPoller" on that server. If it's not, you should open a support case before going any further.