Have you checked the number of lights in range for each (problematic) mesh using mtl_lightcount (or whatever it is called)? mtl_specBump only supports 3 lights, and one of them may be for example the sun if sun_light != 0 and only two other dynamic lights are close (try setting that variable to 0 for the moment).
"Falls das Resultat nicht einfach nur dermassen gut aussieht, sollten Sie nochmal von vorn anfangen..." - Manual
