Thanks - worked a charm

I'm currently editing a large + complex model created in another CAD program for use as a simplified sketchup model.

All its components (and there are tons of them) have their base geometry with assigned materials. I would like to have them instead have their assigned material as 'default', so that I can quickly change their material by using the paint tool when outside the component.

Currently I'm going into each component's instance, selecting all geometry and manually changing it to 'default' material. Is there a faster, automated way to change all base geometry to 'default' materiality without exploding the entire model?