There's nothing wrong with the transformer. This was part of the redesign required for compliance. The transformer cannot have "live power" without the pin in that third position being pushed in. Per the manual, when connecting the transformer to something like a TIU, you have to install the included extra pin into the connector. Unfortunately there seem to be some transformers shipped without that pin included. If you call Customer Service, we can send that pin.
Or you can use electrical tape to replicate the pin 
