There are lots of mowers. There are lots of Craftsman mowers. They are not all made the same so the model number can be valuable information to help us solve your problem. In lieu of that, check the drive belt to make sure its routed properly and nothing is bent. With the mower turned OFF have someone step on the clutch to engage the drive system and make sure everything functions/travels freely. Sounds like there is too much tension on the drive belt. Follow the linkage when the clutch pedal is pressed to see where it goes. Your model may have an adjustment. Good luck.