Credit-shy retail customers are beginning to overcome their fear of buying, according to a number of national department store chains.

Although credit sales are still below their normal percentage of all sales and total sales also are off, customers who shrank away from plastic in the spring are drawing near again.

In part the move back to credit is in response to promotions by department stores, urging customers to think creditagain. Normally in the fall and spring, department stores solicit new credit customers to replace those lost through attrition, but the activity appears somewhat more pronounced in this disastrous year for retail sales.

One of the most common promotions is for sales personnel to ask customers paying by cash or check whether they have or would like to open a charge account.

"I think you will find that most stores and particularly banks are out after new accounts and initiating new accounts promotion," said Nelson Swayback, director of credit operations for Carter-Hawley-Hale, the chain that includes Neiman-Marcus.

During credit controls, which were imposed in March and lifted in July, "new accounts acquisition really had fantastic erosion," he said. "It's amazing how many people felt it was unpatriotic to solicit for new accounts.

For some credit-shocked customers, still trying to sort out their finances, the solicitations strike a slightly ironic note.

For instance, one Northwest Washington couple slowly drifting out of debt got both an overdue bill from Sears, Roebuck and Co. and a letter from Sears on the same day.

"A review of our records shows that you have $1,200 available to you for credit purchases at Sears . . . Perhaps you were not aware you had that much buying power available to you," the letter said. "But it's here waiting for you at Sears, any time you care to use it."

In the same week, the couple -- who almost lost an American Express card over a large, late bill -- got a mailing from American Express asking them if they wanted another American Express gold card. And a call from the Hecht Company asking if they would like to open a charge account.

The Sears mailing was a promotion tool that the nation's largest credit card issuer frequently uses and this is planned nearly a year in advance, according to a spokeswoman.

Although Sears has initiated no new charge account-hunting programs, the company has seen the same pattern in credit sales that other retailers report "Credit sales continue to be somewhat softer than total company sales," said Sears vice president for credit Lyon Wheeler. "The significant psychological impact that adversely affected credit sales in the late months of spring seem to be moderating and we hope it will continue." "We're still processing a hell of a lot of cash, which is a strange business for us," said a spokesman for the Federated Department Stores, which includes Bloomingdale's.

Most stores say they are slowly approaching a normal balance between cash and credit, but none said they are there yet. "When credit controls came in, there was a pullback on the part of the customers, said a spokesman for the May Department Stores, which includes Hecht's. "There is a gradual return to the credit market by those customers." Credit sales for the chain are less than one percentage point below their normal share of sales.

Credit sales are "soft, but we see some signs and trends that there will be umprovement," said Swayback of Carter-Hawley-Hale. "I don't think the improvement will come back very rapidly. Usually when you undergo a government control program like that, it lasts for some time."

Although credit controls, designed to counter inflationary pressures, touched off a sudden constriction in buying, retailers saw a slowdown coming long before controls.

"We saw in the last couple of years credit expanded dramatically, and before March14, when the President imposed controls, we could see there was a tailing off in the amount of buying that we had enjoyed two years prior," said Swayback.

"Credit buying had already begun to go down before controls were put on. Controls just precipitated it a little more rapidly," said George Jones, credit customer relations manager for Montgomery Ward.

Most retail credit experts don't expect the slowdown in credit buying to be permanent and don't see any fundamental changes in customer attitudes toward credit. Wheeler, of Sears, said he expected the most long-lasting effects of the credit crunch to be changes in credit card pricing.

The current reluctance to use credit will disappear, most retailers said. "The American people know they know how to manage credit," said Wheeler.