Update for the end of 2011. Summary
1. After replacing the flow meter, balance valve twice it has stayed fixed for a while, so I am calling it done.
Temperature before removing the flowmeter. We ran the hot water out a faucet for a few minutes to cool the tank and loop pressure.
Collector at 200°F before I removed the flowmeter. The leak at the flow meter after purging yeaterday has not created a problem yet. Why is temperature so high? Well.... Flow is OK, 1.