Bridget , I've been doing some digging and there's bunches of complaints on the Ehpro KFL+ about whistling , some on the genuine SM's too ( makes me appreciate the 3.1's a little more ) but some have cured it by removing the AFC screw , some have had debris in the center post causing it , others have had to sand the air hole on the center post and the base , and others have had to realign the center post to make sure the air ports are properly aligned , if it's the last case you'll have to proceed with caution the center post is easily broken , Get with David , he had to sand his positive block some to get things lined up , seems it's really the luck of the draw on these .
