You are adding a rating so as far as I know you have to get an M1.
Welcome to the world of long queues and $100 fees for applying to make an application for a visa that you will have to pay another $100 for.
Then you will have to pay to register with the TSA, and that costs money too. And then you have to pay (at least, I did) a $30 fee to have your fingerprints taken at a police station close to the school you are training at.
Then there's the "special" sized photos that you have to pay for as "normal" passport photos are the wrong size. Then there's all the money you will fork out going to the embassy - oh and yes of course you have to purchase a DHL or Fedex envelope that they use to post the visa back to you if you get it and.........sigh!
I hope for your sake that it's the waiver but as I said at the start, you are adding a rating and that constitutes training and not just hour building on an existing rating.
Farrell