Every convention has its MEGO (My Eyes Glaze Over) level. And there are signs that the affliction, produced by prolonged exposure to speeches and an aching backside, is beginning to set in for many of the 2,700 delegates to the American Postal Workers Union meeting here.

Although important business -- affecting the future of the postal service, the price of stamps and the fate of the mail-moving corporation's 600,000 workers -- is being accomplished, the little things mean a lot. Normally insignificant, nit-picking items are beginning to take on an unnatural importance.

For example, delegates today shouted down an attempt by a member to force the union to tell its 270,000 window clerk members to stop registering young men for the draft.

The near-unanimous support for post office registration was prompted in part of patriotism, and also because members realize registration provides more work for employes who are worried about budget cuts and automation.

The delegates also ordered negotiators to win a union shop clause in their next contract with the U.S. Postal Service. Under the proposal, rank-and-file workers would have to join a union, or pay dues to it, or lose their jobs. There are more than 600,000 postal workers, and most are voluntary union members.

The popular demand for the union shop could be a problem down the road. The government has outlawed it for federal workers. And the act creating the USPS prohibits it. Nevertheless, union negotiators who begin contract talks early next year have been told to get the union shop or, presumably, be prepared to call a strike.

The three-year contract between the postal service and its unions expires in July 1981. Many observers feel union leaders will be lucky to keep what they have, let alone get new benefits. The present agreement has a no-layoff clause, provides three regular pay raises and cost-of-living salary adjustments every six months. That is nine pay raises in three years.

The value of the no-layoff clause is super-significant here in Detroit. Thousands of workers have been thrown out of jobs in the ailing auto industry, and many families are on relief or have exhausted welfare benefits.

Despite the important issues being discussed, the MEGO factor is responsible for excessive nit-picking from the floor, membership unhappiness with whomever chairs the convention and higher blood pressure readings. One nurse at a Red Cross booth here in Cobo Hall (next door to the site of the GOP convention in July) reported that blood pressure readings have been going up daily since the free health checkup service started this week.

A resolution that would have taken away the right to vote for union officers from individual members, and let the convention do the electing, was defeated. Terry Irvin from the Washington Bulk Mail Center in Largo led the successful opposition. "There is too much politics here already," Irvin argued. "We don't need to tie up the entire convention with electioneering and politicking. Our people sent us here for other things."

Tempers flare each time a potential future convention city is mentioned. Many delegates ask if the location is in an ERA or right-to-work state. A sizable body here is prepared to vote against giving any business to states that have not approved the Equal Rights Amendment, or where laws bar the union shop. Despite this, the executive board has already picked Miami Beach for the 1982 convention, although Florida is a right-to-work state and has not ratified the ERA.

Resolution by resolution, delegates here are building a bargaining position for the upcoming contract talks. The Postal Service will be trying to take away many of the current contract's goodies, certainly the no-layoff clause and also the six full cost-of-living raises for employes.

While management is preparing to tell the typical postal worker that he or she is lucky to have a good, steady job, angry local union leaders are demanding that their bargaining team get better pay and benefits, or turn over the job to militants who believe they can do it.