Nate
A few years ago I purchased a set of brushes to replace a worn out set on my model 541, and although not a convertible, same concept should apply. My friend recommended using a carbon seating stone if you felt brave enough to stick that thing in the motor and it running at several thousand rpm, or you could clean the armature with steel wool as beko suggested above, use a variac (or make one, there are directions on the internet) to run the motor at half speed (approx 55 to 60 volts) for half an hour. That should properly seat the brushes on your motor. If you replaced the brushes without properly seating them and run it at full speed, I imagine you will end up with excessive sparking which would produce more heat, and give off that "ozone" smell. Hope this helps you out.
Steve