hi - i've been having some problems using a displacement map for this model of a radio. I want to use it to add some grooves to the volume dial on the left, however after I add the map the rest of the geometry becomes distorted too (see the red circle in the middle image). the model also has a bump map added as well, but i don't see how that would affect it.

the top image shows the model without the map, the middle shows it with the map and the problem areas and the bottom image shows the displacement map on it's own - as far as i understood, the black areas should have no effect, so i don't understand why the rest of the model is affected.

help!