Contract talks between union leaders and managers of Maryland's major race tracks stalled again yesterday as a strike threat by more than 600 track personnel remains intact.

Union officials were prepared to bargain at Bowie Race Course yesterday in what was termed a full-scale negotiating session. But management declined after its chief negotiator, Michael Milanowski, resigned unexpectedly.

"We agreed that we will get together sometime next week by phone and make arrangements for other meeting dates," said Tom Russow, president of Local 27, the United Food Commercial Workers Union, which represents the workers. "Our committee has proposals from Pimlico and Laurel, and we will study them over the weekend."

Although their contract will expire Monday, track employes have said if there were a strike, it would not be until July 15, opening day of Pimlico's summer meeting. Striking personnel would include mutuel clerks, security guards, parking attendants, admission employes, starting gate crew and jockeys' room valets.

Bowie General Manager Al Karwacki said he was surprised at the resignation of Milanowski, who negotiated the last two contracts.

Even union members complimented Milanowski. Bill Brown, a union representative, said, "He was a good negotiator and a good man. Above all, he was fair."

Milanowski declined to comment on his resignation.

But there was speculation that he might have disagreed with some of management's contract proposals. They include a plan to rescind Sunday overtime pay and reduce the size of the union's collective bargaining unit by excluding security guards, starting gate personnel and jockeys' room valets.

"In my opinion, that is little more than a union-busting measure," Brown said.

Among its proposals, the union is asking for a 10 percent wage increase for the first year.