I have a what I think is a 1975 25 horse johnson model#25R75B serial#E4232849. I had trouble romoving the fly wheel. I removed the nut and put a 3 prong puller over the fly wheel and tryed to pull it off. Instead of coming off, it broke the center hub out of the fly wheel. Did I do something wrong? If so, what is the correct way to pull it off?