I have an Armstrong Dart 140 that developed a slight whistle. I had always tuned the low pressure side but saw a video explaining why you should tune the high pressure side. It made since, so I decided to try it. ~21 sanding attempts later, I now have a stab that gives a great foot massage as long as you wear hearing protection.... and nothing I do seems to help. After a few attempts on the high pressure side, that was just making it 'bad', I decided to cut my losses and go back to what had always previously worked, and attempted to square it off again and taper the low pressure side. Since then, nothing has worked. I seem to make it slightly better, then worse, each time. Now it's just worse. It's like I attempted to cut my own hair and keep trying to 'fix' it... I think maybe I've ruined my stab and long for the days that it had a slight whistle. At this point, I'll try anything because I can't ride it as it is. Need to know if I should just cut my losses, by a new one, and turn this thing into a filet knife. Any help is appreciated. (Not sure the pictures help?... kinda hard to get a clear picture of the edge with a phone)