Ok, then my heli has other issues.
With it adjusted for zero pitch at idle there is absolutely no lift, not even enough to get light on the skids. It's a brand new airframe and brand new motors but old 4-in-1 and old servos and two old battery packs.
Neither of the batteries has been used for more than 30 flights, is it possible they're both dead at the same time? It seems pretty unlikely they'd both die at once... In the space of about 2 flights it went from flying great and having loads of power to barely being able to keep in flight for 30 seconds and fighting for tail control.