V moto monza HELP! I am pulling apart my son's monza (same engine as Yamaha CS50 Jog) following the CS 50 Jog's manual I found on line to replace the O Ring behind the autolube pump as the bike is leaking oil. I have removed the nut and washer retaining the rotor and am trying to remove the rotor with a standard 3 legged puller. This thing will not budge. Am I missing something? I have followed the manual to the letter.