I did some more hunting on the FCC site and I found the documents relating to the denial of WTXX's extension request (thanks to jhe on the AVS Forum for pointing me in the right direction).

The FCC wrote (PDF file/4.8MB - page 154):

In response to our request, you submitted an amendment dated April 29, 2002 stating that WTXX would renew its request to its tower owner, CSM, to pursue the necessary paperwork to secure the local approvals to strengthen its existing tower to accommodate WTXX’s DTV facility. You go on to state that you will encourage CSM to pursue its application vigorously and to provide an updated estimate of the cost of tower strengthening within 60 days of the date of your amendment. You also indicate that WTXX was recently approached by the owner of a new tower that is located on Avon Mountain, approximately 9 miles from the CSM tower, but that these negotiations are preliminary. Based on your submission, we find that you have not taken all reasonable steps to complete construction of WTXX-DT in an expeditious manner. You do not indicate what alternatives you have explored should CSM be unable to strengthen its tower and the Avon Mountain tower site be deemed unsuitable. You amendment also seems to indicate that no studies have been done to determine whether the Avon Mountain site could provide adequate coverage. Furthermore, you do not supply any projected construction completion date. Thus, your showing contains no reasonable plan or projected date by which any DTV facility might be constructed and placed into operation.

For these reasons, we conclude that an extension of the construction permit in this case is not justified and must be denied, with the permittee admonished for its failure to comply with its DTV construction obligations. We believe, however, that WTXX should be afforded until December 1, 2002, to come into compliance with the DTV construction rule. In this regard, WTXX will be required to submit a report within thirty (30) days of this letter outlining the steps it intends to take to complete construction and the approximate date that it expects to reach each of these construction milestones. Absent extraordinary and compelling circumstances, the construction completion date should be no later than December 1, 2002. Sixty (60) days after submitting its initial report, the station will be required to submit a report detailing its progress on meeting its proposed construction milestones and justifying any delays it has encountered. If at any time during this period, the station fails to demonstrate that it is taking all reasonable steps to complete construction or fails to justify the further delays it has encountered, or we otherwise find that the permittee has acted in bad faith, the permittee will be subject to the imposition of additional sanctions. Failure to complete construction of its DTV facilities by December 1, 2002, will result in a monetary forfeiture against WTXX, and the initiation of a six-month process, at the end of which, if the DTV facilities still have not been constructed, absent good cause shown, the subject DTV construction permit will be rescinded.

In light of the above discussion, IT IS ORDERED That WTXX, Inc. IS HEREBY ADMONISHED for its failure to comply with its DTV construction obligations. Moreover, IT IS FURTHER ORDERED That WTXX’s request to extend the construction permit for WTXX-DT IS DENIED, and the applicant is afforded until December 1, 2002 in which to come into compliance with the DTV construction rules as set forth herein.

I also found the letter from the FCC dated April 2002 requesting more info from WTXX prior to denying their extension request in this document DTV Extension Inquiry Letters (PDF/3.4MB - page 505).