Montgomery County Executive Charles W. Gilchrist strode into the auditorium like a college professor, 15 minutes late for his lecture and anxious not to waste more precious time. He stepped onto the stage, posed at the podium next to two huge budget charts, hushed his audience of 100 "students," and urged them all to take notes.

Then Gilchrist launched into a course he could have called "Local Government Expenditures and Revenues in the 1980s," carrying a familiar message: Times are tough, less money is coming in, and even relatively affluent Montgomery is going to have to make tradeoffs to avoid a budget deficit.

Gilchrist has held three of four such "town meetings" across the county, to sell citizens on the need to either cut back some programs or raise property taxes to pay for them. He travels armed with charts and statistics, aided by about two dozen staff members from his budget office and from various county departments. He tells his audiences that if all county services are kept at current levels, allowing for an inflation rate of 5 percent, the county will have a $9.4 million deficit -- and deficit spending is not allowed under the county charter.

Gatherings like Tuesday night's in Wheaton are unusual in a couple of respects. The "town meeting" format is more suited to the small-town, rural area that Montgomery once was, but the central discussion topic is big-city, encompassing a massive $785.6 million budget, which could grow to $824 million next year.

Also, public hearings are traditionally held after the budget is prepared, so citizens can respond to priorities laid down from on high. But in these forums, and in questionnaires being distributed, Gilchrist is asking for citizen input before next year's budget is drafted for submission to the council in the spring.

As expected, he has so far gotten back plenty of suggestions as to where funds should be increased -- education, transportation, aid to the handicapped and the retarded -- while no one has yet made a serious suggestion as to what can be cut.

Gilchrist has said repeatedly he does not want to raise property taxes, although he has not definitely ruled it out as an option.

Halfway through this fiscal year that began in June, Montgomery budget officials are projecting an $5 million revenue shortfall. Finance director Albert W. Gault said $3 million of that came from lower-than-expected tax collections from the real estate transfer tax. With high mortgage rates, fewer homes are changing hands.

Also, Gault said the county lost $1.3 million from what it expected to collect from the deed recordation tax, another sign of the slumping housing industry. At the same time, interest rates for short-term investments have fallen, and the county is collecting $2 million less than it had planned to earn on some of its cash investments.

This year's $5 million shortfall can be covered by the county's $7.4 million surplus, said budget director Jacqueline H. Rogers. But next year, most of that money will be used up.

County budget analysts and department heads are now toying with a laundry list of new revenue raising ideas. One proposal is for a so-called "Pac-Man" amusement tax on video games, which would be passed on to the players. Officials are also looking at ways to increase fees for some recreation department facilities, tennis courts being often mentioned.

Rogers said the administration is reviewing a range of possible new and increased user fees, from the cost of checking out library books to receiving services from the county's health department.

"The health department is a fertile field for fees," she said, "because they service middle-income as well as lower-income clients."

Gilchrist's last town meeting is scheduled at 7:30 p.m. Monday on the Germantown campus of Montgomery County College.