I seem to recall that the USAF dictated the ADF must not be switched to the next aid (company procedure?) and as a result the 737 continued to back track on the NDB behind it instead of once passing that NDB, bringing the ADF to the NDB in front of it. That latter NDB I think was needed for the missed approach. Result being the aircraft was tracking inaccurately and more and more off the inbound published track. The reason for the company procedure was purportedly to reduce the chances of the crew mis-selecting the NDB ahead. Difficult to believe the curious reasoning by whoever dictated this limitation.