Well, this was quite the anniversary present! I have had my bike ONE YEAR TODAY and in celebration of it's first birthday, the woodruff key fails. Happy, happy, joy, joy. I logged 2600+ miles in 2003 on my WR450 with NO problems. I didn't have the TSB performed and thought I was one of the lucky ones to not have the woodruff key failure. Well, it happened to me today and I was SHOCKED! Unloaded the bike and went to start it and it just wouldn't go. A couple of pops, sputters and the kicker starter was kicking back and then nothing. The starter was just spinning and I knew I had become an official victim. Took the bike apart at the parking area and called a buddy who was coming out later to pick up a new key at the Yami shop on his way out. Replaced the key, torqued it to spec and put 20 miles on it with no issues. When I pulled the cover, the flywheel nut was about ready to fall off. I think this failure is my fault and I'll tell you why. When I pushed the flywheel onto the crank, I really had to pull hard to get it back off. So, I believe I have well-matched mating surfaces on the crank and the flywheel. The bike is jetted well and hasn't back-fired since I have owned it. What I have neglected to do is check the torque on the flywheel nut at regular intervals and I believe that had I checked it on a regular basis, I could have avoided this. Should I have to do this? I don't think so but with the shady history of the 03's and the flywheels I guess I will make this a monthly ritual from now on. Will the 04 upgrade parts help this issue? I'm not sure but I will definitely mull it over. I will tell you this, though...I will be packing several spare woodruff keys in my fanny pack so I can fix it trailside.