I soldered a new motor driver with an IRL 510 mosfet. I did this because the transistors I used got too hot and burned out. The driver for the left motor works with the old motor. So I can now build the driver for the right motor in the same way. The mosfets don't fit inside the mouse case, so I made a new tiny board which will be placed on top of the SD card module. This isn't pretty but will work. Also the board has connector pins soldered in for more easy handling of the cables that are connected to it. This looks more professional as my direct wired boards before.