Congratulations on your acheivement.
If it has been fifteen years since you last tested, I would contact your local tech school for training classes to prepare for the Masters exam.
Tom Henry's system is very good. Does not teach what you already know, just how to pass the test. http://www.tomhenry.com
You probably took the 8 hour exam when you passed the journeymans?
Here in SC. you can take the test every Saturday, 4 hrs.
Two tries for same price.
Great to hear your a motor guy. Not many around that really understand them and their controllers.
Apply for the test as soon as you start the preparation course. You want to test asap after the class. "when I got my masters I finished the class on a Wednesday, and then tested the following Saturday".