Japanese television manufactures said yesterday that because their imports no longer pose a threat to the American television industry, the U.S. government should suspend a 9-year-old dumping finding which requires special monitoring of thier goods entering the U.S.

But American manufacturers said removal of the dumping restrictions could lead to a flood of imported televisions from Japan that could mean the demise of the U.S. television industry, which already has dropped from 17 American-owned firms in 1970 to six.

The International Trade Commission, at the request of Sanyo Electric Co. Ltd. and several other Japanese television makers, began hearings yesterday on whether to change its ruling in one of the largest trade cases in the United States.

The Japanese manufactures said yesterday that since the government found in 1971 that the Japanese manufacturers were dumping television sets here, many of the companies have opened assembly plants in the United States and export very few sets from Japan to the United States. Seven of the 14 television manufacturers in the United States are owned by Japanese firms.

The Japanese manufacturers argued yesterday that dumping regulations require enormous amounts of paperwork that is unnecessary because they are not dumping and no longer pose a threat to the U.S. television industry.

Dumping is the sale of goods at prices below their production cost that injure or threaten to injure a domestic industry. A dumping finding requires the assessment of sometimes large duties and requires monitoring of the imported goods.

The finding has been outstanding for 10 years," said H. William Tanaka, an attorney for the Electronic Industries Association of Japan and the Hitachi companies. "We have to revoke the finding so that people won't have to be burdened with the administrative task of collecting information for agencies charged with administering the dumping act. It's a headache, basically."

The 1971 dumping decision led to a nine-year disagreement between the importers and the U.S. government over how much the importers should pay in dumping duties. The major imorters finally agreed last April to pay up to $77 million to the government in outstanding dumping and civil fraud claims.

The 110 importers of the sets agreed to settlements of claims on $2 billion worth of television sets imported here between 1971 and April 1, 1979. b

The Committee to Preserve American Color Television, which opposes suspension of the dumping finding, contends that the Japanese have reduced the number of televisions exported to the U.S. because of the fear of being assessed more dumping duties.