At one point in my brief career at Bell, I was assigned to flying the 'flying whirl stand' Bell 412.
We had a 'rogue' blade that wouldn't track, and in desparation, I had the mechanic watch while I changed airspeed at the same power setting. The blade went way out of track, and we ended up using balance weights against the tab at the outer tab. That worked.
Not sure if that will help your situation, but every little bit helps.