We have a GE 7H2 generator and have been changing out brushes every 6 months during our seasonal outages. The electricians does not feel comfortable changing brushes online and are a baseload unit. Is your site brave enough to change brushes out online or do you wait for a shutdown? Also what is the frequency? We run at high lagging MVARS, near the OEL limit which really shortens the life of the brushes.