I have a minimax 400 heater attached on a spa only.It use to work fine,but now will not ignite.All seems the same except the burner does not fire up.The control valve ,I think is working,because I felt it click when I turn the switch on ,or with the switch on,turn the temperature control.Looks like the likely thing is the igniter,not sure what type it is and looks like.I am used to working on water heaters only.I would think that before the thermo coupler is bad it would be an electrical part.Just thought someone had some history with this unit and a suggestion to help me.thanks for your help and time.Dave Taylor