Your grass is growing???????
WOw!
I just put a little STABIL additive in my gas tanks every fall when I put the mowers away until spring.
I ADD a small amount of carb cleaner to that gas before starting it up. It will clean the carb and combustion chamber while running.
I generally don;t have much gas in those tanks either...
But, carbs do gum up sometimes so I see why the carb cleaner, plus its combustible....
Man, for a guy in his nineties you really do a lot!!! lol!!!!!