I know several people who got the 'M' endorsement who never took the motorcycle exam. You could be 'grandfathered-in' if you simply asked. At some point in the past few years, they changed the law without really notifying anyone.
It didn't matter at that time, you only needed a driver's license to ride a motorcycle, so I never mentioned it. At some point in college (I think) I noticed the 'M' endorsement for riding a motorcycle wasn't there anymore. About 1982-83 when I was 14 or 15, I got a motorcycle license. I've mentioned this before, and I only get more ****ed the more I think about it.