You probably won't as the GMC operation went broke
I am led to believe that ozito took them over so there is a possibility that the ozito hammer drill will use the same brushes
It is worth a try
other than that, many electric motors use generic brushes so may be an appliance repair shop that has a lot of repairs to hand drills and small electric motors may be able to supply a set of brushes
a sample would be a big advantage when asking around