Trane L.P. furnace burners don't all light
I put in a used Trane furnace that was working in another house ( on L.P.) It worked good for a week or so, now when the gas valve opens only the first two burners light most of the time, then gas valve closes since the burner by the flame sensor isn't lit. It stays lit if I help the flame spread across the other burners with a torch, but it only works on its own about one time in ten. Does the gas valve need to have the pressure adjusted, or is that even possible? The propane tank still has 200 gallons in it, and they checked the main pressure regulator when the tank was filled last time.