Marilyn Greene of Arlington writes, "I hope this will not reach you too late. Before writing to you, I spoke to subway station guards about the problem, and two weeks ago I called the Metro Complaint/Suggestion office about it.

"Imagine taking the escalator down to the subway platform at Farragut West during the rush hour and then finding that the platform at the bottom is so crowded you can't get off!

"This is not a nightmare, something I dreamed. It is a fact. It happens to me about once a week during my evening rush hour trip home.

"The Metro attendants turn off the escalators as soon as they notice that a condition of this kind has developed. But during rush hour they are very often busy fixing broken farecard gates and answering questions, so how can they be expected to watch the escalators every minute?

"In my call to Metro, I suggested that the escalators be turned off at the start of every rush hour, not just when the attendants happen to notice that a dangerous condition has developed.

"The situation at Farragut West contains all the ingredients for a serious accident resulting either from the crush of people at the bottom of the escalator or the danger of people being pushed off the platform into the path of a train. Can you do anything to help?"

No, I can't, but I know a man whose mission in life is helping to make the subway run properly. His name is Harold W. (Harry) Barley, and he's assistant to Metro's general superintendent for rail operations.

Although it was almost 11 p.m. when I got to Marilyn's letter, I phoned Harry at home and read the letter to him. His response was typical of him.

"Thank you for getting this information to me so promptly," he said, "I'm almost positive that instructions have already gone out to the attendants at Farragut West to stop the 'down' escalator on the Virginia side at the start of every rush hour, but I'll check it out first thing in the morning to make sure the memo has reached people who work there and that everybody has been clued in on what they're supposed to do.

"The Virginia side of Farragut West is the most hectic spot on the rail system at rush hour. The government has done a pretty good job of staggering working hours, but most of the riders who board at Farragut West appear to get off from work at almost the same time. The big rush doesn't last long, but while it's in progress it's really hectic. It is obviously dangerous to permit escalators to continue to deliver people to a landing area at which there is no room for them, so we must take steps to see that it doesn't happen. I'll get on it first thing in the morning."

Marilyn, I'd be willing to bet 10 million billion trillion dollars that you will find the escalator on the Virginia side turned off during this afternoon's peak period. However, if it is not, you'll have to take my IOU until I can cash my paycheck. GROWING PAINS

Bruce H. Burnside of Rockville has sent me a clipping from our sporting department's "Sports on the Air" section. One listing stated that Channel 4 would carry a baseball game between Chicago and "1/8CZin1/8cZinnati."

I can accept this more placidly than the average reader because I happen to know that our sports section has just gone "on the computer," and that a few typographical mixups are absolutely unavoidable. It takes computers a few days to become accustomed to being operated by strangers.

I am also inclined to take a charitable view of 1/8CZin1/8cZinnati because I was raised in Zinzinnati. I become annoyed only by misspellings that put two t's in the word. The Z sound is heard so frequently in Cincinnati's Over-the Rhine district (as in, "Vass you effer in Zinzinnati?") that no native gives it a second thought.

In any event, I hope that District Liners will be patient with us during the next few weeks as additional departments and groups of writers begin using sophisticated new video display terminals.

As soon as we get the hang of how to use our super-smart hardware, I hope we'll be able to give you a better newspaper faster. We have also put 2,001 pounds of money (which is even more than "a ton of money") into a new printing plant in Springfield, Va., and this, too, will speed late news to more homes more quickly.

When we goof, you may find it hard to believe that we really care about doing our jobs well. But you can take my word for it that we do. Scout's honor. We didn't win more than a million readers a day by not caring. THERE'S ALWAYS A CATCH

Herm Albright of the Perry Township (Ind.) Weekly reports that residents of China have hit upon a wonderful new reducing diet.

"You eat all you want, but you're allowed to use only one chopstick."