To answer the thread starter, Kaarlo:
The effect you're describing is called "cogging" and has nothing to do with the motor's overall efficiency. The key to how/why the cogging feels is due to the number of magnets (poles) and the number of stator arms.
I too own an X-era (4035-2.5Y 480) and it is a monster to turn by hand. It's all because the magnets are always opposite stator poles (arms) directly. Each permanent magnet has a direct and unopposed attraction to an iron stator arm. Other motors using more or less magnets have a different ratio of arms to magnets and only a pair of magnets will be directly lined up with stator arms at any one moment whereas all the other magnets are either getting ready to line up or have passed the point of direct alignment. Follow? The Actro series (32-3 and 32-4 in particular) have their own unique magnet configuration -- each magnet (pole) consists of paralleled magnets sitting directly against each other in eight sets. I guess it works
My Kyosho e-Caliber 90 uses that X-era motor mentioned above and there are times I can't take advantage of the autorotation clutch to let me move the main rotor out of the way of an object. So how do I turn the rotor in reverse? I give it a firm and constant bump against the "compression" of the motor's magnets and keep a steady push on the rotor until it moves to the desired angle. Don't worry about hurting the drive gears -- if they can take the strain of flight, they can easily take the cogging of the motor.
So many heli's - too little time...