I have an older Johnny Pro. All of a sudden it began making a loud noise, like a bang, from the area near the sprocket. this occurs approximately every 1.5-2 revolutions of the pedals.
I have investigated, but cannot pinpoint the problem. It may be that the bearings/washers/whatever between the sprocket and the body of the bike are worn. I tightened the bolts at the base of the pedal, hoping that would do the trick, but no. I then removed the bolts, trying to disassemble the sprocket connection, but I can't figure out how to take it apart; nothing moves.
Looking at it from above, it appears that the sprocket wobbles a bit and that there is an uneven space where the bearings are. I still cannot tell exactly from where the noise originates; my daughter thought it was when the chain was trying to right itself on the crooked sprocket.