The cable TV industry today made an image-boosting move designed to appease countless current and would-be subscribers with busted hook-ups who've had to wait days for help. Starting March 1, the National Cable Television Association announced, customers will get $20 for missed or late service calls, and prospective viewers will get the line installed gratis if technicians miss or come late to an appointment. The pledge -- which could cost the industry $10 million -- isn't binding on cable firms, but the trade group says virtually all of the nation's 11,000 cable systems plan to honor it. Why? The association says poor service has created a "credibility gap" with consumers. Not mentioned: Deregulation has cable and telephone companies racing to get into each others' businesses, and cable faces a potential threat from a new wave ofwirelessandsatellite delivery systems.Post your opinion on theNew Mediabulletin board.