Update March 3, 2010: CNET testing points to the extent of the black level increase in affected plasmas. Click here for details.
"Since the TVs work as designed, there's nothing to fix."
That answer comes from Bob Perry, Senior VP of Panasonic Consumer Electronics Company, in reply to a follow-up question CNET asked in response to the company's February 3 statement addressing reports about the company's plasma TVs losing their deep black levels over time.
That statement maintained that the plasmas' black levels are designed to brighten over time ("background brightness will increase from its initial value") to compensate for the normal aging process, but suggested that picture quality was still "excellent" after the compensation period was complete and the "internal material characteristics...stabilize."
In a February 5 phone call with CNET (also attended by CNET editors and Bill Schindler, an independent engineering consultant for Panasonic), Perry confirmed that the company has no plans to fix anything related to the black level-related complaints with its current plasmas. He echoed the explanation in the original statement and elaborated somewhat on the black level increase. He likened it to rotating the tires on a--an example of standard maintenance--and said that some users noticed the change "because they have trained eyes," although he also said that the change is subtle "even among trained experts."
He did not go into specifics on many points, however, claiming that some answers might give away trade secrets and that lack of standards for black level measurement make it "very difficult to make meaningful comparisons."
He reiterated that owner satisfaction was very high and that the vast majority of owners don't notice any change at all. See the end of this article for the full text of an e-mail sent by Perry the morning of February 9, with Perry's complete responses to CNET's follow-up questions.