An automatic egg injection machine comprises a separate injector support grid and injector locking device. The injector locking device is attached to the body of the egg injection machine to prevent motion during the vaccination process. Individual air tubes are inserted into slots in the injector locking device, and are inflated with compressed air to lock the injectors in place during the injection process, thereby minimizing the possibility of injector movement. Both the injector support grid and injector locking device can be exchanged for other components with different egg configurations so that one egg injection machine can be used for more than one sized incubator egg flat.