''I'm willing to try anything to keep this show on the air,'' says Models Inc. cocreator and coexecutive producer Charles Pratt Jr. ''But one can get very depressed.'' And with good reason: Although Models is at a point in the ratings similar to where Aaron Spelling-produced sister shows Beverly Hills, 90210 and Melrose Place were at their five-month mark, and though Fox has ordered enough episodes to carry the series through February, the spin-off is still looking for the formula for success. One character, it seems, has been sent on a permanent vacation (Brian Gaskill's David Michaels), a writer has departed, and the implausible story lines that made daytime soaps seem restrained are being dropped. ''We branched out a little too much we have too many psychos and weak links,'' Pratt admits. ''When you have weak links, you have to take a sharp right.''
The turn, in this case, is to soap veteran Emma Samms, who joins the largely inexperienced cast next week as villainess Grayson Louder (estranged wife of James Wilder's Adam Louder). Fox is already touting her as Models' Heather Locklear. ''Talk about pressure,'' says Samms, 34, best known as Fallon Carrington on Spelling's Dynasty, where she costarred with Locklear. ''I will do the best I can, but I can't concern myself with whatever expectations there are.'' Backing up Samms is a new game plan for luring viewers: more romance, + more modeling, and more personal traumas. ''It's a daily battle,'' says Pratt. ''At some point we're going to stop worrying, and then things will inevitably get better.'' Cheer up, Chuck: No one watched Melrose the first year, either.