The oval lids are all interchangeable. If the thing doesn't seal well there are a number of things you can do besides keg lube. First take a look at the keg feet. If the rubber caps are worn, you may want to replace them. If you don't want to replace them you can stick a coin under the feet. Another solution is to bend the legs a little so they seal a little tighter.
Sometimes the edge of the lid is bent a little. Put the lid on a flat surface and you should be able to see any dings. If bent, a light tap with a hammer will usually fix it.
You should also check the lid gasket. Old gaskets may crack, harden, or become permanently compressed. If so, just replace the gasket. If that still doesn't work, you can replace it with one that is a little thicker. I get these from http://www.williamsbrewing.com/KEG_L...O_RING_P58.cfm
These are slightly larger and softer than standard O-rings and do a great job of sealing stubborn lids. I have them on 3 or 4 of my kegs.
Hope these tips help someone.
Bugeater Brewing Company