Sarah Jessica Parker tries to save her low-rated law drama, Equal Justice, during a recent appearance on Good Morning America, asking fans to write ABC on its behalf. Viewers of the imperiled Dark Shadows send 7,000-plus letters to NBC. On both coasts Barnabas partisans picket the network's headquarters, carrying mini-coffins and signs that warn, ''Don't Stake Dark Shadows.''
Yes, network decisions on the fall slate of shows are due in late May, and fans have already started to inundate the webs with imploring missives. Just how much mail does it take to keep an endangered series from extinction? Fifty thousand letters to CBS saved Designing Women in 1986. In 1988, 3,000 telegrams in a 12-hour period convinced the same network to keep Beauty and the Beast alive. Yet even the 10,000 pieces of gripe mail that brought back Twin Peaks to Thursday nights last March may not give the doughnut-driven soap a third season. Have the networks wised up to letter campaigns? ''They're not effective,'' says Ray Faiola, director of audience services at CBS. ''They identify themselves very easily. We pay more attention to individual reactions'' meaning that a lone Nielsen point is the equivalent of 931,000 households. But the cards and letters keep coming. ''If you don't have a Nielsen box, there's only one avenue,'' explains Viewers for Quality Television president Dorothy Swanson, ''and that's your typewriter.''