Stopped in their tracks two years ago in their attempt to take over the Avemco Corp. of Bethesda, Jacques and Morrie Zinman have agreed to sell their Avemco stock back to the company and drop a law suit which had charged the firms officers with mismanagement and misrepresentation.

Under the terms of a settlement announced yesterday, Avemco will pay $4,875 per share for the Zinmans' holdings, which total 94,500 shares. The price is more than 25 per cent below the book value of the shares, but above the average $4 price at which the stock has been trading on the American Stock Exchange.

Avemco also announced a tender offer to existing common stockholders to purchase up to 300,000 shares at the same price being paid to the Zinmans.

All parties involved in the law suit have denied allegations of wrongdoing. The reason for the settlement, they say, is to avoid the cost of protracted litigation.

The Zinmans, who live in Jenkintown, Pa., were part of a group of Philadelphia insurance executives - under the names Zinman Grossman Lichtenstein Co. Retirement Trust and the Mutual Fire Marine and Inland Insurance Co. - who by early 1975 had amassed 6.5 per cent of Avemco's outstanding shares. They then notified the Securities and Exchange Commission of their intent to gain control of Avemco.

To counter that move, Avemco's management proposed certain charter amendments designed to thwart takeover bids and asked shareholders to vote on them. The Zinmans, who said they were acting in the interest of all shareholders, filed a class action suit to block the vote. The suit charged Avemco's officers with trying to entrench and perpetuate their control.

Avemco is the largest general aviation insurance firm in the world. It also owns other insurance and finance firms engaged in marketing, management and real estate.