Are the lights working? If not, it may be the lighting coil. Check it by disconnecting the plug on the wiring harness coming from the mag and check the ohms with a meter by probing the two yellow wires. Reading should be 0.18 ohms.
lights are working but I don't think the bat. is charging. I haven't even taken any reading with my volt meter yet. The reason I don't think the charging system is working is because the After running it there is no power to start the sled with the electric start if it took a few times to crank it initially.
Easy test, you should get 12.5vdc at the battery at idle and 13 - 14bdc at 3000 rpm.
If you are not getting this, check the battery for dead cells, check wiring for a blown fuse, check that you are getting power from the rectifier.
You can have one side that is still providing power for lights, but the side that feeds the battery can be blown.