It could be possible that your sidebelt is too tight. Like the previous person said make sure the pulleys are in good condition and make sure they are not too tight. They just need to be tight enough so they don't slip. The side belt you can run pretty loose. I did have a problem once when I mixed up the pulleys and put the wrong one on and that caused some problems. You should make sure that you have the correct pulley in the right place too. Hope that helps.