Why didn't you just change this through Edit Node? Go to Manage Nodes, select the nodes you want, click Edit Properties, then change the Polling Engine.
Prior to NPM 10.2, you had to stop the services so the jobs would be re-scheduled. If you are running NPM 10.2 then changing the Engine ID should be fine and you don't need to restart the services (but you should update your signature :-) ). If you are running something before 10.1 you should restart the services so the jobs will be re-created for the new engine.
I am currently on NPM 10.1.2