RE: Eflite Blade CX
As Psikelly mentioned, check the gear mesh, also, try adding a drop or two of light oil, graphite or teflon spray to the gears. If this doesn't fix your problem. It may be a motor going bad, they only last 20 or 30 hours, if longer your ahead of the game. Also, try lubricating the shaft bearings.
Hope this can help ya,
Dave / Choppersrule