one possibility: If it stops at the same position for a given hand, the hands may be getting caught on a dial feature.
otherwise, something more ominous going on inside. if you can tell us a little more about the watch, and where you got it from, we can davise on whether servicing will be worthwhile. generally speaking asian 21 j movements aren't worth the trouble servicing b/c the labor costs more than the movement.
If its an ETA or ETA copy movement, you can find a rep friendly watchsmith locally, or otherwise send it to vacuum or ziggy.