[mentorDon]

Try using a process of elimination to find where the clicking noise is coming from. First disconnect the chain and run the motor with gears. If the noise has stopped, must be coming from the chain or onward to what ever is connected along with the chain drive.

Second, a long wooden dowel (36 x 1/2") will work wonders at locating noise origins. Hold the dowel up and pressed firmly to your outer ear. By moving the dowel around touching different parts, sounds will increase or decrease depending how close you are to the noise. However you must use some common sense and don't place it between the sprocket and chain or any other place that it can be grabbed.