Materials you'll need:

o Matchsticks or toothpicks
o Wood glue
o Metal angle brackets and screws
o Scraps of ply
o Sandpaper
o 4 blocks of wood the same thickness
o Replacement set of table legs and fittings

Tools you'll need:

o Fine saw
o Sharp pointed tool for scribing

There are few things more annoying than a table, which rocks whenever it is used. The annoyance can also turn into a real problem if a loose screw or broken brace is not diagnosed and fixed.

First check and tighten any loose screws. If the screw hole has enlarged and won't hold the screw, remove the screw and pack the hole with matchsticks or toothpicks dipped in wood glue and replace the screw.

If a corner joint is broken, repair with a metal angle bracket, screwed underneath the frame, below the old wooden bracket, or bolted into the corner.

If legs are still wobbly, attaching a wooden block or a metal plate to the underside of the table as close as possible to the leg can strengthen them.
To test the table legs, stand the item on a level surface and rock it with your hand to see if it stands level on 3 legs. Use a spirit level to check this. If it will stand level on 3 legs, the fourth may be too short. Lengthen by removing the leg and slipping a scrap of ply between the leg and table top, then replace the leg. Alternatively, glue a small piece of wood to the bottom of the short leg and trim and finish to match the others. If you wish to level the table by cutting down the other legs, mark the amount to be taken off very carefully and use a fine saw.
Cut the legs a little longer than you think is needed and sand back to the required length, a little at a time.
When one leg is longer than the others, a way to measure the amount of wood to be removed is to stand the table on a firm, level surface. Cut 4 blocks of scrap wood exactly the same thickness. Put one under each of the even legs and place the fourth block so it rests against the uneven leg.
Using the block as a tool rest and guide, scribe a line around the leg with a sharp pointed tool. The leg can then be cut accurately around this line and the table should be level.
If table legs are beyond repair, replace with ready-made legs from a hardware supplier. They usually come with brackets, which fix to the underside of the table and the legs screw into these. It is usually easier to replace all four legs than try to match the existing legs.