Rototiller starter cord retracts violently
We have an old Ariens Rototiller that is generally in good condition. It was just returned from anual servicing but came back with new problems. The scariest is that when I pull the starter cord, every once in a while it is tugged back into the mechanism very suddenly and violently. It didn't start. Yesterday, I thought I had broken a finger when it did this. The cord is in good condition. Now I'm afraid to even try to start the machine until I know it is fixed properly. Any suggestions about what I should do?