I'm no expert, and only have my own bird to compare with - and it's been on over 60 flights with no problems.
When stationary (no power connected), main blades manually adjusted to 0 deg, tail blades manually adjusted to 0 deg (don't force the servos if they don't wanna move, then just power it up and do it with the Tx in throttle hold);
Give the feathering shaft spindle a good twist (CW). The blades should now spin freely, and should spin at least one or two turns before stopping. There should not be any noticeable noise, you will hear the one way bearing, but that shouldn't be very loud.
Pick up the bird. Take a grip with one hand on the main gear (not the one way gear). You should be able to turn it ever so slightly from side to side (CCW/CW). There should be a very low clicking sound as the main gear teeth stops in the pinion teeth.
You can turn the main gear (CCW), but you should have to apply some force; as the pinion is also turning. You should turn the main gear one whole rotation (360 deg). The amount of force which is applied - has to be consistent all the 360 deg.
You can also hold the bird up in the air, and look at the alignment of gears (pinion-one way gear-tail gear) when spinning the blades CW. There should not be any wobble in gears, and the gears should line up horizontally to each other.
Hope this makes any sense!
Good to see you've not given up
