After another crash the original brushed motor was bust, so I decided on attempt to make it brushless. Tracing the circuit for raw CH3 PWM turned out fruitless so far, but I've discovered the internal brushed ESC (just a simple chip) is itself PWMdriven. The throttle stick has thus only short valid track, as seen in the video, but unless I track the raw CH3, I'm going to fly it in this configuration.

Using: 1108 brushless motor, cheap 12A ESC, 3024×3 propeller.