IF YOU'LL BEAR WITH US while we bring up a sore subject for the umpteenth time - namely, the Union Station-National Visitor Center-Amtrak terminal - Congress needs to do something about its right away, before adjournment. The Senate already has done something, by voting to authorize the spending of $60 million to make necessary repairs and readjustments on the place, as well as to build a new intercity bus terminal there. In the House, however, more modest legislation approved by the Public Works Committee has yet to come to the floor for consideration. And if it doesn't, you thank Committee Chairman Harold T. Johnson (D-Calif.) for the additional construction costs caused by letting the bill die.

True, the whole project has been a fiscal horror show from the start, a saga of inflation, labor problems, cost overruns, inadequate supervision, a lawsuit, a bankruptcy and poor plans.Now it's purely a matter of a salvage operation - and the Senate has recognized this sad fact with a sensible bill to do what needs to be done. The repairs have to be made, the railroad station needs to be set up properly to handle the passenger loads of the future, and all that wideopen space for visitor services needs to be put to better use. Though we prefer the Senate bill to the House counterpart, there is room for compromise.

We are well aware that it is late in the day for an agreement. But the differences in the bills are such that they could be resolved sensibly, fairly and in short order by the legislative managers. The important thing is not to let this tedious rescue effort collapse in the home stretch, for it will be a long, expensive - and dreary - legislative experience if Congress has to start all over again next year.