Some background, why the solution works without changing the timer prescale:
The default prescale of all timers are 64, so they should work the same, but the default mode is different:
Timer 0: Fast PWM mode = 0..255,0..255,... (timer is used for internal calculations millis() / delay() /..., so this setting is required)
Timer 2: Phase-correct mode = 0..255..0..255...
Timer 1 is 16 bit and the pins are blocked by the radio, so I'll leave them out here.
The frequency of the timer is comparable to a timer round trip (values are calculated with a 16 MHz IO-frequency like with ATmega168 or ATmega328 used in nano):
Timer 0: 16 MHz / 64 / 256 = 976.5625 Hz
Timer 2: 16 MHz / 64 / 510 = 490.1961 Hz
Fast PWM uses 0..255 = 256 for a round trip.
Phase-corrected mode uses 0..255,254..1 = 256 + 254 = 510 (all numbers are double except 0 and 255!)
NOW the command:
TCCR2A |= _BV(WGM21);
Switches timer 2 to fast PWM mode (mode from 1 to 3).
In addition to the links above, here I found the default settings: http://playground.arduino.cc/Main/TimerPWMCheatsheet
