Let us rebuild your 10 tooth Onan Starter motor. Since these are not available new at this time, we do have the parts to rebuild your unit. Email or call for availability. Some companies say the 9 tooth will replace the 10 tooth. Not so! From what our customer's tell us, replacing a 10 tooth with a 9 tooth, only makes the 9 tooth grind and shims are needed to get the 9 tooth to work correctly. And, where that Starter is located, you don't want to be messin' around under the engine trying to get the Starter to engage correctly!