help, 2006 kx250f no spark

I am fixing a 2006 kx 250f for a friend and it has a few problems that have me stumped because I have never had them go wrong on any of my cr or yzs. The first problem is I have no spark. I got a new plug and checked it in my yz to make sure it works, but that did nothing. I swapped the coil/ sparkplug cap to the yz to make sure that worked. Checked the wires from the plug to the CDI box with an ohm meter and those are fine. I tried unplugging the kill switch to see if that was the culprit, but still no spark. Then I come across my second problem. I pulled the magneto cover off to see if there was anything visibly wrong in there and I found what looks like a half moon shaped shaft key stuck to the inside of the flywheel. Any idea where that would have came from? The bike has 30 hours on it and has never been apart before. The only place I know that uses one is the flywheel but I don’t see how it could come out. I am getting a puller today to check it anyways but it seems very strange. As far as the no spark thing goes I am going to try swapping a CDI box off and 07 kx250f to see if I can get some spark (any changes from 06-07 that would not allow that to work?), and how do I check the magneto?? Never had one of those go bad so I don’t know where to start? Thanks in advance guys