Arrived at location on 10/1-21 - Checked unit found air vent in regulator clogged. Pulled and cleaned. Blew out air hole. Flames are still low but not dropping as you turn others on. Checked gas pressure was 2.5 " set to 4.5 and flames are normal now. all bypass flames set to 1 1/2" turned them off and brought temp to 200 then set bypass flames to 1/8". Checked calibration and left t stat locked in place. couldn't get to move. Middle was ok right t stat was on or off. Will order left and right t stats. unit is operational. Flames and pilots won't go out. Requires parts. Returned to location on 10/5/21 - Disassembled unit and removed far left thermostat and far right thermostat. Installed new in their place. Turned gas on to unit and lit. Allowed unit to reach temperature and calibrated. Adjusted thermostats and bypasses accordingly. Unit in service.