USPS Address Standardization returns errors when using the USPS production server

The iInitial problem when saving a contact with the USPS Address Standardization system enabled was that the following error message is returned: "USPS Address Lookup Failed with HTTP status code: $code " The system does not report the status code, just the string "$code"

Working with dlobo on IRC we were able to remedy this initial error by changing the ' to " on line 78 of CRM/Utils/Address/USPS.php. The resulting editied line is as follows:

$session->setStatus( ts( "USPS Address Lookup Failed with HTTP status code: $code" ) );

After implementing this code update, a new error occurs. We now get: "USPS Address Lookup Failed with HTTP status code: 403"

I have verified with USPS that we are using the correct USPS Production URL, that our USPS account is active and authorized for the production server and that the USPS servers are up and responding correctly. Debugging the USPS.php file is beyond our current capabilities, but, we would be happy to help test any code updates.