[Zee]

If you have cracked aluminum spinner and you have to fly with it, use small drill bit ( like # 60 ) and right at the end of the crack drill thru the spinner, debur the hole so there is no sharp edges. It is called stop drilling
It is important that on the spinner cut outs , there is no sharp edges or rough edges, with the vibration that is a good place for crack to start.
Zee