The groundswell has trickled to a standstill.

Ticket sales for the Washington Capitals, who must sell at least 7,500 season tickets to stay in business and in Washington, have slowed considerably in the last few days. Through yesterday, the hockey team had sold 4,520 season tickets, 3,600 of those renewals from last year's 4,200 season-ticket holders.

Sales of single tickets to the Capitals first 10 home games total 12,321.

For the team to operate this season, according to conditions set by potential investors, the first 10 games must be sellouts. That means approximately 85,000 tickets must be sold in addition to the projected 7,500 base.

Lew Strudler, the team's marketing director, admits sales have slipped somewhat. Last Saturday, the team sold only nine tickets.

"It's difficult to address oneself to hockey when it's 95 degrees outside," he said.

But a television editorial addressed the Capitals' situation last Friday and Monday. Rich Adams, editorial director of WDVM-TV, criticized the request by Abe Pollin, the team owner, that Prince George's County reduce the amusement tax (from 10 percent to one-half of 1 percent) on the Capitals.

In addition to 7,500 season tickets and 10 sellouts, Pollin said the would-be investors wanted a decrease in the rent at Capital Centre and a reduction on the county amusement tax.

The county council has not yet voted on the request to reduce the amusement tax.

Adams said Pollin has already received "big benefits at public expense," as Capital Centre stands on public land, and had received property tax breaks during its first years of operation.

" . . . When (the county) is laying off teachers, cutting social services and generally crying poverty, should the county council give away any more tax money to a private business? . . . Pollin is selling a product--professional hockey. People don't seem to be buying," Adams said.

Adams said yesterday he had received some irate letters from Capitals fans.

"I'm not against the Caps," he said. "But our point is this: if the team was just starting out, fine. But the county has already given them so much. Pollin is in business, and I don't think he should ask the taxpayers to subsidize it."

Adams said a televised rebuttal from a Capitals spokesman probably will air later this week. Yesterday the team had no official comment on the editorial, but Strudler said, "Any type of editorial has to have some effect."

He said the team is counting heavily on the business community to make up ticket deficits. Last week's mass mailing by the Washington Board of Trade to its members is expected to increase sales among companies.

"If companies come in with about 2,000 season seats, we'll make it," he said.