By John S. McClenahen For months the Washington-based National Assn. of Manufacturers has been putting a very positive spin on the demonstrably slowing U.S. economy. But now, Jerry J. Jasinowski, the 14,000-member organization's president, and W.R. (Tim) Timken Jr., its chairman, are sounding more bearish than bullish. The possibility of the U.S. economy moving beyond a soft landing to a hard crash is significant, says Jasinowski. "There is no guarantee of a soft landing," he stresses. Meanwhile, Timken, who's also chairman and CEO of the Timken Co., Canton, Ohio, believes "we are a little worse off than we think we are." Lower order levels caused Timken to lay off 60 workers during the last few days and trim capital spending plans for 2001. Timken himself expects inflation-adjusted growth of the U.S. economy to be a very slow 2% in 2001. And he wants Chairman Alan Greenspan and his Federal Reserve colleagues to loosen up monetary policy. "It is absolutely essential that the Federal Reserve move promptly from its current tightening bias to a neutral bias . . . and consider cutting the [federal] funds rate by 25 basis points early next year.