How can I fix my Makita Angle Grinder?

I appear to have overloaded my makita 9069 angle grinder cutting through some concrete. It cut out,gave off some smoke and an acrid smell. Whenever I now try to turn the powertool on, the motor turns but then blows the fuse. I have cleaned the armiture and bushes and although the disc spins freely with an initial burst from the motor it still blows the fuse. Is it possible to diagnose from this description where the problem is likely to lie and is it fixable.