I have a Bunn Dual 120/208 brewer and after the heating elements turn off the water temperature is only at approximately 180-185F and the green ready lights don't turn on. This model is from 2003 and I recently bought it used. Everything else seems to be working fine except the water temperature seems to be a bit low. If I have read online correctly, the temperature should be about 200-205 in the tank and about 195 (+/- 5 degrees) coming out the spray heads. I put a thermometer directly into the tank and verified it's only at 180-185. Any ideas what's causing this? The temp probe in the tank has some light green corrosion on it but it doesn't seem too bad. The thermostat control knob is also turned completely on. Any input would be appreciated!

Coffee Makers & Espresso... - Bunn - Dual® (20900.0011)