Q: I would like to know what, if anything, can be done to increase the tension in the spring balances of my double-hung windows. These have springs instead of the old-fashioned sash cords. The upper sash won't stay in place when the window is not locked.

A: If you have the long cylindrical or tube type spring blances they can usually be tightened by first removing the screw the holds the tube in place against the wondown frame, but hold the tube while doing this so it doesn't spin or snap out. When the tube is loose, you can wind the spring in the inside tighter by turning the housing with the screw still in place in its hold then refasten against the window frame in the orginal position. If tightening in this manner doesn't work, then chances are the spring is broken and must be replaced. If your window have the type of spring balance that consists of a revolving drum at the top with a metal strap coming down to the side of the sash, then there is no adjustment and it will simply have to be replaced.

Q: A corner broke off one of my concrete front steps. The piece that came off is pie-shaped and broke off cleanly. Is there a way I can reattach it to the steps so it will hold?

A: If the break is clean and there are no large gaps, you should be able to cement the piece back in place with twopart epoxy adhesive. This comes in tubes or cans and in clear or various colors. I recommend the clear [actually amber] because it will be least noticeable. Make sure the surfaces are clean and absolutely dry, and follow mixing directions on the package.

Q: We have a small Chippendalestyle end table with a mahogany finish that is somewhat darkened by age. I would like to put a Chinesered lacquer fnish on this piece. Must I strip off the present finish entirely, and what kind of paint should I Use?

A: Whether or not to strip the finish will depend on the condition of the old finish. If it is reasonably sound -- not flaking, cracking or peeling -- you can paint over it. If it is cracked and dried out, or if shows signs of breaking down, it should be removed. If you don't remove the finish, it should be thoroughly sanded and all wax or polish should be removed by wiping with solvent. Dust thorougly and apply a good enamel undercoat. Finish with two coasts of high-gloss red enamel, sanding lightly between coats of after adequate drying time has elapsed.

Questions about home repair problems should be addressed to The New York Times Syndication Sales Corp., 200 Park Ave., New York 10017. Questions of general interest will be answered in this column, but unpublished letters will not be answered individually. CAPTION: Illustration, no caption, By Bethann Thornburgh The Washington Post