A.J. Gee
I had the same problem with a Mamba max and Vortex. But there is no solution, you have to purchase a new Castkle motor or a new speed control with sensor.
I recommnd you to get the Mamba 6900 motor and keep your Mamba max speed control. Castle creations controls can be programed via USB and there is nothing compared to that in the market.
cheers!