The fascination of a pinball machine is a baffling to some as it is unthinkable to others.

The thunks, beeps, chimes and staccato bursts of the scoring mechanisms can ravage the sense, as can the grotesque, large-bosomed women of the back glass and the gyrating, machine-slapping rituals of the players.

The sounds of pinball, for others, can be pure harmony. The music is to be called from it comes only with long practice and a maestro's entreaties.

More people are discovering this. In the last two years, the production of pinball machines has increased about 30 percent. There are about 200,000 in operation around the country. It's estimated that $500 million is spent annually on pinball plays, to say nothing of sales of home and businesses. Most play for fun, diversion, but some get quite serious.

When a good player masters a machine, the psyches himself to make it do what he wants, he can produce such exquisite moments as when a single steel ball dances for three, four, five minutes at a time - a blissfull eternity. This kind of magic has been prevalent in the 1978 Maryland Pinball Wizard Tournament, a 10-week statewide competitions culminating today and tomorrow at the Lord Baltimore Hotel in Baltimore.

Sample: A Wednesday night in Prince George's County; eight semi-finalists gather at the Gateway Fun Center, a game room in a small shopping center on Marlboro Pike. WPGC blares. Bong. Bong. Kachunk. Whack. Dat-dat-dat-dat. A 22-year-old warehouseman named David Warden, black, short, muscular, pesrpiring (a hand towel hangs from the back pocket of his jeans), is producing the first magic of a night of pinball that will last until early morning. The ball shoots around the playfield - crazily to some, precisely to his peers who gather close to the machine.

They say, "We're gonna need a fire extinguisher to put this thing out . . . Slow down, fella . . . He's making it do what he wants . . . Aaaah . . . " Warden style (he keeps pumping his left knee), confidence (he brings the ball to a complete stop and cradles it on one flipper), and, if he cares, everyone's attention. And he has dignity. When the ball finally drops off, he hangs his head slightly and olds his arms. No oaths, no hitting the machine. The others, step up. "Way to go Dave . . . Good play, Dave."

The place, Gateway Fun Center, and the machinery there, ultramodern, tell more about the resurgence of pinball than the players.Similar game rooms in shopping centers have suddenly become common around the country. This one is bright and clean - and strictly run by a former P. G. County policeman, Jim Wilkins. "No drinking, no smoking, you don't lean on the equipment," he says.

"It used to be, the first thing you thought about when you mentioned pinball was a bar, something bad, where people hung around, did wrong. Now these plush centers are springing up all over the country.

"I got business people come in to play, to relax, take some of the tension off."

The game, in the last two years, has caught on with middle and upper classes, professional people.

Pinball is big abroad, also, especially in France, where it's called flipper, pronounced "flea-pair." French importers are ordering $25 million worth of American machines annually. Jordon's King Hussein reportedly has had three American machines sent to him.

It's the new machinery that seems to lure everyone from kings on down. The traditional electromechanical games are giving way to machines with solid-state electronic components. Wood frames have been replaced by stainless steel. Leaning on his Sinbad game, Wilkins say, "It has a hell of a memory system in it. It doesn't forget a thing. It remembers a free game, extra ball, everything that happens on the playfield. It doen't forget to take your quarter either."

The game, perhaps most significantly, has become legal in major population centers. Though Fairfax County last year banned further installation of coin-operated amusement machines in small retail stores, pinball bans have fallen in recent years in other places - New York, Los Angeles, Chicago.

"Vert intriguing, pinball games," says Wilkins. "I think they're intriguing to everybody."

One player roars up for the P. G. semifinals in his white Ford. Glen Mitchell, 16, says, "The whole exhaust system dropped off Saturday night." He talks quickly, excitedly. He hits the Burger King across the street, then sits outside the Gateway picture window, waiting for the action. (The tournament is sponsored by the Amusement and Music Operators of Maryland and sanctioned by Sefco Distributing Co. of Hanover, Md., and States Sales and Service Co. of Baltimore; top prize in each of two divisions in the finals is all a pinball player could ask - a new Williams or Bally pinball game.).

Dave Van Valkenburg, 21, a book-keeper, backs up his polished brown Mustang directly out front. Tall, imposing, he strides in and surveys the place, Old West gunslinger style. Heads actually turn to catch his entrance or a glimpse of his blond date. She says, "You know he was Pinball Wizard of the month in March."

Nobody merely walks up to a machine to play. Van Valkenburg goes into a knee-bending, leg-stretching routine, as if warning up for some athletic contest. Another player apparently shedding tension, stares toward the back glass, extends his arms, arches his back David Warden's run is the first big one. David Van Valkenburg matches it, and another crowd gathers. "You're going to need a fire extinguisher to put that thing out."

"Dave's (Van Valkenburg) the kind of player," says Wilkins, "who'll take any machine right out of the box and he'll tear it up."

Seven hours later, at 1:30 a.m., it's official: these two Davids finish one-two. They both win a trip to Baltimore.