Deborah Brown has lived in the town of Upper Marlboro for five years. In that time she has taken an interest in community affairs, but has never voted in a town election.

It's not that she hasn't tried. Brown has not voted because she isn't registered. And she isn't registered because there is only a single day--and just four hours--every two years for new voters to register, and she has missed both chances.

Town elections supervisor Anna Buck and her distant relative, Ruth Buck, who sits on the tiny town's three-member commission, view Brown as a troublemaker, one of a group of newcomers who want to change things.

"There's a bunch of new people who have just come here and don't even have a right to vote yet," an angry Anna Buck said. "They're the ones stirring up all the trouble."

Upper Marlboro, the seat of populous Prince George's County, is a small town (about 300 residents if you don't count the 440 inmates of the county detention center), and the profile of its government is flattened by the overwhelming weight of the county bureaucracy, which brings about 4,000 commuters daily into the government buildings along Main Street.

Tradition and the way things are done are important to the people who live there. Strict residential zoning laws have kept the town small, despite the presence of the county government. "Not many people move here," says Helen Wilson, who as president of the three-member town commission is the undisputed power in the town bureaucracy. "We don't need that many registration days because not that many new voters arrive."

Despite Brown's interest in voting, the town's elections are not followed with great attention. A county newspaper, the Enquirer-Gazette, ran a small story after last January's election, but none during the campaign.

"I didn't even know there had been an election," said Margaret Hinson, who lives in the town. Neither did a woman who has worked for 21 years at the information desk of the county administration building. Like others questioned, they didn't know that a separate registration was required to vote in the town election.

An undetermined number of voters elected Wilson to a third successive two-year term, along with Ruth Buck and lawyer Jess Smith.

Neither Wilson, Smith nor Ruth Buck knows how many votes they got. Anna Buck says she knows, but said this week, "I'm not telling you."

The normally placid meetings of the commission were disrupted last month when Deborah Brown and her husband, Daniel, showed up to ask that the registration rules be changed. During a heated discussion, Anna Buck called Daniel Brown "filth and scum."

According to minutes of the meeting, the commission, under some pressure from Smith, voted to permit registration every office day between 9 a.m. and noon, the commission's normal office hours, beginning July 1. The commissioners also agreed to place an announcement of the change on the front page of the Enquirer-Gazette.

So on July 1, Brown and two other newcomers, Yvonne Moore and Anne Gross, showed up to register. There was no one in the office, but a police officer on duty let them in, and after a while Smith appeared.

He called Anna Buck, who said she could not register anyone that day. Ruth Buck came to the office, but told the women that she could not help them because she was hurrying to a vacation in Ocean City.

The would-be voters then tried to reach Wilson, but Ruth Buck said Wilson was in court. Despite the commission's action last month, Wilson now says the next opportunity to register will be "sometime between now and the next election, one-and-one-half years from now."

Anna Buck doesn't understand what all the fuss is about: "Can you tell me what people would want to register for, if there won't be anything to vote for until January of 1984?" she said. "Isn't that the silliest thing you ever heard?"