Hi it's kind of hard to hear on the nitro blizzard ...when i had mine i drove it on the street and you can see the blizzard jerk a bit when the gear switches... you may have it set in second gear all the time...if i recal with mine it switched gers in like 3 feet or so because it is so torky due to the low gear ratio...
You should feel it switch though..... what you need to do to see if it is working ...just don't nail the gas go slowly on the trigger reving the motor up slowly this way you will hear and see if it actually is kicking in gear.