So I had this intermitent problem for the past week. 2 out of 3 times, the solenoid would not engage the gear when cranking the starter. Starter spins but not engaging the flywheel. I knew it was something simple. All it took is a relaxed two hours of a sunny afternoon, a few basic tools, some solvant and lub. After the clean-up, the starter spins smoother, faster and engages all the time. I didn't disconnect the positve wire at the battery as it would have required to pop the filled GSA gaz tank. I simply put some duct tape at the connector after unbolting from the starter. Attention must be given to cleaning up old gunk from the solenoid, reduction gears and the sprocket. Just be carefull with the dowel pin when you reinstall the starter. You want the starter to be perfectly seated.