When you say you put a new pull start in... do you mean you jsut replaced the black pull start part ?? or did you remove the backing plate from the engine, and remove the turbo fan that connects to the con rod?
If you just replaced the black pullstart part then yeah i'd say there's something wrong with the one way bearing (this resides in the turbo fan). One way bearings are pretty hit and miss... the reason i turned to a starter box was because you no longer need a one way... starter boxes are pricey though...