First of all, always keep the reps to 5 or less on the power clean. Preferably to 3 or less. You don't want failure to ocur due to technical breakdwon as these olympic lifts are "athletic events" themselves. As for getting stronger it's 1/2 technique and 1/2 just being strong. At 100 lbs I'd say you need to get stronger overall. Put 50 lbs on your squat, front squat and deadlift then watch your power clean come along for the ride.