You will need to take the transmission off to gain access to the clutch take off the clutch spring or springs depending upon which clutch you have and work the clutch with your fingers and make sure it works freely.
Make sure that there has not been any oil grease or two-stroke that has infiltrated into the clutch and spoiled it.
Make sure that there has not been any oil grease or two-stroke that has infiltrated into the clutch and spoiled it.