The Great Redskinette Cover-up apparently is upon us.

All those navels and backs on display when the Redskin cheerleaders unveiled their new costumes Sept. 10 at RFK Stadium are being altered to expose less skin, according to Joel Margolis. Redskin assistant general manager.

That diamond-shaped hole on the tummy portion of the uniform will be covered over with net mesh. And more material has been added "to give us a little less exposure. Margolis said. He wasn't smiling.

"The girls should never have been allowed to go on the field because they were not properly attired," Margolis said. "It was just bad judgment. But they got the uniforms only an hour or two before the game. Some of them didn't fit properly, but it was too late to do anything about it.

"Yes, I was upset. As soon as the game was over I went down and told them they better do something. I just thought they went a little too far.

"We don't want a sex show. We want attractive girls, nothing more and certainly nothing less. The new costumes, once they're fixed, will look great. But they've got to be fixed to fit the way they're supposed to be fit.

"No one should have been able to see the bellybuttons, and they were cut too short, much, much, much too short.I think you can dress girls to look sexy, but you sure don't have to show everything, I don't believe in that."

Edward Bennett Williams, Redskin president, has not said anything publicly but reportedly made it clear, in no certain terms, that he wanted to see some changes made.

One Redskin fan, Marilyn Fausnight, wrote a letter to Williams after the first home game. "I question why a person cannot be retained who has the talent to design a sexy and chic outfit for our Redskin cheerleaders," she wrote.

"The coup de grace is the diamond-shaped, navel-exposed cutout. Navels come in all shapes and sizes, none of which are particularly attractive in my estimation. It's rather like elbows; we all have a set, but who wishes to direct blatant attention to a bunch of folds of skin . . . I would forego navel exposure and bring back the good, old-fashioned cleavage."

In a letter to Fausnight, Williams wrote: "I share your feeling that the new uniforms of the Redskinettes are most inappropriate and have directed that they be replaced."

The Redskins appropriated $3,500 for the new uniforms. Margolis said they now are being altered for use during the Redskin game against the New York Jets Sunday at RFK Stadium.