You'll have to locate faces that have low texture scaling values, < 0.2 is usually problematic.
If you can't find the offending value(s), you can use my ConvMap utility at
http://user.tninet.se/~xir870k to set a minimum texture scaling value. Beware that this might make some textures look misaligned. But that might still be easier to fix than manually finding the culprit face(s).
The best thing is if your editor can help you trace bad scaling values, e.g. I think QuArK can do that.