What kind of spark tester are you using??
I use one like this:
https://www.napaonline.com/en/p/BK_7002015
And open it to a quarter inch (compensating for the fact that it’s harder to make a spark under compression) and I’m not satisfied unless I get a blue spark and a good “snap” sound.
After sanding the points, I always clean them by running clean paper dipped in acetone thru them.
http://www.omc-boats.org
http://www.aerocraft-boats.org
