Hi Szilard,
I have no experience with flybarless however here are some observations:
1/ The main gear may have suffered damage due to missalignment/overpressure with the drive motor. It will need replacing, when doing so adjust the motor position so that the gears are centred on one another and fit snuggly without forced pressure. The discolouration on the gear is an indication of an issue, I applied a match head of lithium grease this eliminated noise/heat/friction for smoother running.
2/ Source some new servos, price is not always an indication here. I used HK15178, cheap as beans, I bought 6 and have 4 in perfect working order(no slop) for my eventual rebuild.
3/ Ditch the wood/plastic rotors, nearly impossible to get a perfect balance, opt for f/glass or c/fibre.
4/ Take all your rotors off and runup the heli after you have dealt with #1 and look for any imbalance or slop in shaft bearings and rotor head, then strip the rotor head and check main shaft and feathering shaft for straightness by rolling on a glass surface, any imperfections here you will need to replace the shaft. Even a 0.5mm imperfection here can translate, once back together runup without rotors to check.
I could hear the blade tracking/pitch was way out, perfectly balanced c/fibre or g/fibre blades with 0 pitch at 50% throttle will make little noise.
Tip1:
Find each blades mid (balance) point, a perfect drive shaft on a glass surface is good for this, now add tape to one blade so that both blades midpoints match from the tips. Mark the midpoints for future reference.
Now match the weight of each blade by adding tape to the midpoint of the lightest rotor.
Tip2:
Purchase some turnbuckles to assist with blade tracking, finer adjustments can be made. I sourced mine from
http://www.miracle-mart.com/store/index ... a35449fbd1Hope this is something for you to start with