Fly speck flaws are not always recurrent flaws in the plates.
You would first have to sort them out by printing dates,
then you can see if you have any of the recurrent plate flaws.
In the Sociedad Filatelica de Chile link you have a list of these flaws and retouches.
Look under PRIMERAS EMISIONES 1853-1866.
https://www.sociedadfilatelica.cl/S...emision.html