KaotikH2,
The one-way in the motor is slipping. I had the same problem and Horizon just told me to clean it. I did and it works for a while. I'm not satisfied, in my opinion the one way, or the shaft that it is turning is faulty. Rather than take the backplate off the motor, just try squirting some carb cleaner in the carb intake. When you do this turn the motor, by rotating the flywheel, so that it is on compression. Doing this will uncover the hole in the crankshaft and allow the cleaner into the crankcase. Now tip the car so that the cleaner will find it way to the rear of the motor. Try the electric starter now, its should turn the motor over easily now!