The one way bearing is behind the pullstart. If you take the pullstart off carefully so the assembly doesn't come apart and the spring doesn't pop out. If it's not grabbing then it's either worn or it's possible that it's coated in oil. Take the bearing out and spray it down real good with WD-40 then take a small amount of nitro fuel in a small jar, put the bearing in the jar with the nitro fuel and swirl it around in the jar a little bit take the bearing out and let it sit and dry out. Clean the pull start shaft off. Put the bearing and pull start back on and it should work good again, if it doesn't then the bearing is probablly out.