What could be the reason to have a Dingo "down on power", ( from normal APC 16x12 - 8600 rpm CP 30% Heli to 7600 rpm ). I've noted that the disc valve ( piece 29 )came loose time to time because the retainer screw ( piece 31 ) unscrew itself. Than i adjust the clearence between disc valve and back plate and screw again the Retainer screw, and the motor goes ok. But after 2 or 3 flights came again the same problem.
What could be the major reason for that?