Poor fitting between burner tube and control valve - advice needed

[wally774]

I'm a DYI'r and I replaced the thermocouple in an A.O. Smith model GCVL 40 100 but am having problems reconnecting the burner tube to the control valve. The flare fitting that secures the connection between the burner tube and the control will not grip the threads well enough to make a secure connection. When trying to re-assemble it, the flare nut won't grip. The unit is 12 years old but this connection functioned adequately before I disconnected it to replace the thermocouple. What else should I try? Thanks in advance.

 

[Mr_David]

If the only thing you replaced is the thermocouple then it should go back in.
check alignment of the flat tab on end of burner tube to make sure it id inserted properly into the slot provided for it inside the burn chamber.