NEW YORK -- In the twilight of the typewriter, as IBM sells its Selectric division and secretaries trade their trusty electrics for word processors, the old man known as Mr. Typewriter is all keyed up.

"We're getting more work than we can handle!" says Martin Tytell, 76, whose Tytell Typewriter Co. and Questioned Document Laboratory has identified, made and repaired typewriters for everyone from the FBI to Alger Hiss.

The other day a tribe of Indians in British Columbia asked him to make the first typewriter in their language, and in the past month he's sold eight Romanian typewriters. A Japanese company opening a plant in a region of China with irregular electrical power wants 20 manuals in phonetic Japanese.

There are calls from companies trying to track down the authors of anonymous memos, from lawyers wondering if a will typed out on a proportional spacing electric could really have been drawn up in 1950.

Tytell and company -- his wife Pearl and their 45-year-old son Peter -- are ready for virtually any typographic challenge.

They have the world's largest collection of type -- about 2 million pieces -- representing 145 different languages and dialects. They have about 400 assembled typewriters in various languages, including several in Hindi and Siamese, ready for sale.

They have a type and typewriter reference library that helps them to determine, sometimes for the police, whether a document could have been typed on a particular typewriter on a particular date.

But their greatest asset is their experience. They can tell a Selectric II from a Selectric III by the length of the underscore line. They know that if the dot on an "i" is slightly to the left it was typed on an L.C. Smith manual, that an "8" with a small projection at the top came from an Underwood Model 8.

Tytell has made or repaired machines for Dwight Eisenhower, Adlai Stevenson and Andy Rooney. He has made a typewriter for one-armed typists, and a machine with nothing but question marks for a client who, he recalls, "may or may not have been sane."

Martin Tytell's interest in typewriters dates back to high school; he would regularly take apart the old Underwood in the physical education office, and the repairman would regularly have to put it back together. Finally, the expert let Tytell in on a few secrets, and soon the youngster could reassemble the machine blindfolded.

He started his own repair shop before World War II, and hired Pearl, who became his wife five years later. When Martin was drafted the Army put him to work making typewriters in the many languages used in the war's many theaters. The war ended, but not the need for unusual typewriters.

In 1950 Tytell was hired to buttress a claim by accused spy Alger Hiss that he was the victim of "forgery by typewriter." Hiss's attorneys posed the ultimate challenge: Duplicate the famous Woodstock N230099 on which documents that incriminated Hiss had been typed.

For the then-enormous sum of $7,500, Tytell worked for months to create such a machine. In the end, a judge ruled that Tytell's effort was less than a perfect duplicate -- a verdict the machine's creator questions.

By the late 1950s Tytell's fame was such that the Post Office routinely delivered mail addressed merely "Mr. Typewriter, New York" to his dusty, cramped office-lab-warehouse-workshop near Wall Street.

There, steel shelves reaching to the 11-foot ceilings are filled with typewriters, spare parts, boxes of type and equipment ranging from microscopes to blowtorches.

Three years ago the floor began to collapse, so the Tytells rented another space around the corner. The family collection extends uptown to Peter's one-bedroom apartment, which shelters about 130 typewriters -- "but a lot of them are portables," he explains.

On a recent morning the clan gathered to discuss their favorite subject. Martin's long white lab coat matched his moustache and hair; Pearl wears her hair wrapped around her head in a braid; Peter looked scholarly with his wire-frame glasses, droopy moustache and necktie decorated with type faces.

They love their work and love to talk about it -- usually all at once.

When Peter, who launched into a history of the typewriter, mentioned that Queen Anne granted the first patent for "a writing machine" in 1714, his father jumped in to correct the date (1713, he said) as well as the patent number.

The interview was suspended as father and son began pulling reference and history books from the shelves; finally Peter located a history of typewriters in German that proved him right and ended the argument.

Today the computer printer is replacing the typewriter as the favored instrument of white-collar crime, extortion, ransom and blackmail.

In his more sanguine moments, Peter tells himself the printer is merely "another cycle, another swing of the pendulum," and that the basic laws of document identification haven't changed. But, he adds, "If I don't take that attitude I'll be reduced to a mass of Jell-O."