We have a wind up mantle clock, and it runs to slow. How do we fix this?

This clock doesn't have a pendulum bub... whatever that is. I looked up help and it said something about the pendulum bob. But apparently our clock doesn't have one. This clock isn't antique, old, but not antique. I think the name of it is Hamilton or something... anyways. Winding it up doesn't do anything except for about 10-30 minutes after we adjust it. Advice, tips, and web links are great! :D thanks!