dvl12, you can try this at your own discretion, you say the lens will not retract completely. Try giving the lens a helping hand/ give it a moderate push with the palm of hand when it is retracting. This may get it past the the point where gear is slipping and reset it in proper position. Place clean paper between lens and palm to prevent dust/smearing lens.
I hope this helped you out, if so let me know by pressing the helpful button.