STRUGGLING to strike a balance, the seven in Houston offered yesterday a few thoughts -- although not necessarily their final word -- on aid to the Soviets and the Chinese. They committed themselves, the seven said, to working with the Soviet Union as it tries to create an open society -- but that's not a promise of grants or loans. They saw some flickers of improvement in the Chinese government's performance, but it's going to have to go a lot farther, particularly in human rights, before the seven fully lift the sanctions imposed last year.

The United States, rightly, doesn't intend to offer cash aid to either the Soviets or the Chinese. Secretary of State James A. Baker made that very clear in his press conference. But the declaration by the heads of the seven big industrial democracies doesn't seem to bind all of them uniformly. There's going to be more on the subject today. The declaration, and Mr. Baker's commentary on it, seem in effect to be a progress report on the action, two-thirds of the way through the meeting.

The American position, as Mr. Baker expounded it, is that all seven want to see perestroika succeed and the United States thinks that technical assistance -- meaning advice rather than money -- is the best way to help. But it's the Germans and the Japanese, with their huge trading surpluses, who now have the greatest capacity to extend financial help.

Foreign aid has many purposes. It often leads to commercial advantages for the donor, a consideration in Japan's proposals for China. It can buy a measure of stability for an economy in trouble, a thought much in Europeans' minds as they apprehensively watch the decline of living standards in the Soviet Union. The West Germans hope, in particular, to buy Soviet acquiescence to the unification of their country. From the beginning the purpose of these discussions in Houston has been, not to impose a uniform policy on all seven countries but to set reasonable and agreed limits on the differences among them as they deal with the Soviet Union and China.

The appeals for help from the Soviet Union, this country's great adversary for nearly half a century, open questions of great depth and political fascination -- so great that, if these seven governments are not careful, they might become the center of the deliberations at this annual meeting. It's necessary not to forget that the most important business before them lies elsewhere. Houston is the seven's best and probably last chance to resolve their corrosive quarrel over world trade rules -- an issue that is familiar, grubby, tiresome and crucial.