Newbie with heli problems

[Jay]

Hi, this is my first post, i wish my forst post could be on a more positive note, but i have a problem with my little co axial heli and i am hoping someone may be able to help.
Firstly the model is a Opal Kyanite, i joined another forum to see if someone may be able to help, but all i got was that this heli is a cheap POS toy and that i should get a better more expensive heli, infact everyone seemed to suggest getting a Blade MCX, i almost wondered if it wasnt just a sales site for the blade. i happen to like the look of mine more and i know it does fly well when it works properly!
I am hoping i will have more luck in this forum.
Ok, so the problem im experiening is on taking of it keep flying backwards and spinning, ive read abouit the toilet bowl effect and its like that, but in reverse! its not a trim issue, becuase i think if it was the trim it would be turning on its axis, where as im experiecing a spiraling backwards flight with the nose holding the same heading.
I have only had it 5 days, it flew great for the first 4 days even after it had expereinced a few crashes (well im completley new to flying rc helis and dont have much space in my flat, so it was bumping into walls and the ceiling quite often, so im wondering if its had one knock to many and has caused some kind of problem inside, Ive taken it apart and cannot see anything untowards, no loose wires or things rattling about.
I replaced the main rotor baldes as the leading edges were a bit ragged where they have hit things, i thought that might affect the flight performance but new blades havn't fixed the problem.
There is something however that i now think may be the cause of the problem.
There is small amount of up and down movement of the inner rotor shaft, sorry if i am not explaining it better, but if i gently hold the top of the rotor i can move it up and down a bit and that makes the lower gear cog also move up and down, which i think will cause vibrations, thus affecting the flight performance, question is, can it be fixed or should i just buy a new heli! it wasnt to expensive and may work out cheaper than paying for repairs.
Hope somone may have some suggestions for me
Thanks

Jay

[Jay]

Here is a video showing the problem, its easier to see it rather than trying to explain it!
http://www.youtube.com/watch?v=HGC9ZhEkreA

[mtpenguin]

hard to say on those little guys.

any slop anywhere will cause issues...

blades balanced?
any hair, fuzzballs around the head, cyclic?
swashplate separating?

B-)

[mtpenguin]

bent shaft(s)?

If you take the blades off, and power up, do the main shafts vibrate? (bent?)

B-)

[Fireant]

The co-axial works but having the blades, which are fixed pitch, rotate in opposite directions. This makes the helicopter very stable and cancels out the gyroscopic torque effect. Dorectional control is then done by changing the speed of the blades together with the little motor on the tail.

Yes, it is likely to fall into the catagory of cheap helis, but there are so many clones it is difficult for a novice to tell the difference although the price is generally a giveaway.

However, the blade grips (the metal pieces holding the blades onto the shaft) should be rigid. If they are moving on the shaft, they could be causing the strange flight behaviour.

Firstly, I would try and fix the grips. If this looks like a no go, then take/send it back to the supplier (if you can).

[thumbtime]

i have one outside i will look in the morning see how much play in the topblade/inner shaft but i think there is a little screw inthe btm gear may need loosening to slide the gear up to take out the play however 0.25 off slop will be ok rather than tight fit which will eat batt/motor