Goodman Furnace Rating Cleaning Flame Sensor On Goodman Gas Furnace.?

Cleaning Flame Sensor on Goodman Gas Furnace.? - goodman furnace rating

I have a Goodman gas furnace in 1997, I think it effieciency for 98%. Last year I had the flame sensor clean, and again this year. Is this a widespread phenomenon? I clean with fine sand paper should be doint something else? The frequency with which the self-cleaning oven? I do not know what has never been cleaned, at least I know he has in the past 5 years I've lived here. Is this something I could do, if not, what would normally a business?