I have rebuilt a few of these motors and I have replaced a few. Is there something wrong with the motor or do you think it is just getting weak and tired? Depending on the hours on the motor, it may cost more, but beneficial in the end to replace the motor. I would recommend getting the model and serial number off your motor and either go online or call
http://www.jackssmallengines.com and
http://www.repowerspecialists.com. I have bought from both in the past and they were very reasonable in price. If you don't think much is wrong with the motor, maybe just tired, you may even call around to other local golf courses and see if they have a mechanic or equipment tech looking to do some side work might be willing to rebuild it. I am down near Dayton, and may know somebody and I will check with him.