This dryer was turned over to me for minor sheet metal repair and it runs well but when It is hooked up to my propane bottle for test the flame is bright yellow. Usually when I test gas dryers on propane the flame is slightly blue not yellow. Should this be more of a blue flame and if it needs adjusting what area should I consider adjusting or changing. The jet orifice in the valve is the type for natural gas to my knowledge. Any advice would be greatly appreciated. The unit s/n is 1102030073. Help !!!