how to check a float

Are they all made the same?
IMO, I can't imagine a particular weight as a gauge to go by. I'm thinking buoyancy needs to overcome a pressure in a given range for the application. The know the outboards on my six pack tend to weaken over time.
Is there a flooding issue? Is it adjusted properly? How old is the float?
20 bucks for a new float is cheap compared to oil changes due to a weak float.