Have you ever moved a game around? No, I mean REALLY moved a game around? You know, that little "walking cabinet" where you rotating the entire game on one corner foot, then do the trick again with the other corner. Ever do this on cement? Then you know why you often see leg levelers worn so much that the screw head is peeking through the bottom of the metal "foot".
Leg levelers are what keeps your precious cabinet from touching the ground. Without feet, moving the games on the ground can cause splintering and denting of the cabinet. The ground isn't supposed to damage your cabinet, that's what you're moving dolly is for ;-).
When I'm done with a restoration and about to place a game in its finally resting place in my collection, I check the condition of the leg levelers.
Carefully place the game on its back and check the leg levelers. If their screw heads are peeking through, or their bottoms are bowed out, then it's time to replace them.
Usually leg levelers are held into the cabinet by what are know as T-nuts. These T-nuts are usually held in by large metal "staples" (at least, that's what they look like). If the T-nut is rusted to the point where you can't remove the leg levelers, you can do whatever rusty-bolt-remover technique you prefer, but to me, that's usually a sign to replace the whole shabang. You can get new T-nuts from a hardware store or amusement distributor. The standard size T-nut for video game leg levelers is 3/8".
If the wood is not rotted or water damaged, you should be able to get by with pulling the metal staples and reusing them when you replace the T-nut. Often, however, you'll see a case where the entire leg has bent over and destroyed the T-nut hole, or water damage or rotting has made it impossible to mount a new T-nut. If this is the case, you will be better off using a leg leveler plate. These plates are not as easy to locate; Happs sells 3/8" thread steel leg leveler mounting plates for $2.50 each, or 12+ for 2.00 (might was well buy three games worth). If the bottom is too rotted or splintered to mount the plate flush, you can try mounting the leveler plate from inside at the bottom of the cabinet where hopefully it's not as bad, otherwise you may want to consider just replacing the whole bottom of the cabinet!
Ok, so now you've got nice new leg leveler mountings where you need them, so screw in the leg levelers. The standard arcade game uses 3/8" leg levelers (makes sense), and 2" long should be long enough for most applications. Screw them in to the desired depth; this is really a matter of taste, and may depend on the cabinet. I usually like an inch between the floor and the bottom of the cabinet.
Getting the cabinet actually level is another trick. If your game is now rocking back and forth, you'll need to do some sort of cabinet balancing act while you try and adjust the levelers. There are all kinds of tricks to level the cabinet, like resting the cabinet on top of boards, then adjusting the levelers down until they touch the floor, or you can use a flat pry bar to leverage up the front of the cabinet and adjust the levelers, or just have a friend tilt the game while you make adjustments. Whatever works best for you.
Play a few games to check your work. Done!
New leg levelers
leg leveler mounting plates (optional)
Happs has some nice leg leveler mounting plates available, as well as most styles of leg levelers. T-nuts are available from most hardware stores.
For home collectors with tile or wooden floors, you'll want to put extra protection between your floor and your games. Wal-Mart carries leg leveler cups, which are rubber pads that fit snug around the feet of leg levelers. Apply them with a little glue so they don't fall off incase you move your game a lot. However, if you move your game a lot, you may want to consider removing your leg levelers and T-nuts and mounting some appliance wheels to the bottom. However, I wouldn't want to play Robotron this way :-).