I have a kohler starter (nippondenso type), which seems to hang almost every time the key is turned. I have taken it off, had it cleaned and replaced the solenoid. It works great on the bench. When I put it on the motor, it just doesn't seem to engage the flywheel. You can hear the solenoid pulling in hard and the starter spins fast.Does anyone know of anything that can go wrong with the gear the engages the flywheel. I wondered if it can wear some, so that it is harder for the teeth to engage the flywheel. I have checked and the gear that engages the flywheel is not slipping. I have several of this type of starter and after a while, they all at this same way. As I mentioned, I have purchased new solenoids for three of them and none will work when on the mower. When I put a new starter on the motor it works fine, so it isn't the electrical system. Any suggestions are appreciated. Kohler offered for me to send one of the starters back for testing and I may take them up on the offer, if I don't figure something out soon.