mahcyb , The video links below will show how to remove the plastic drive wheel on your Magic Bullet and replace it(take note the threads are back wards to most, turn right((clockwise)) to remove/loosen) and anti clock wise to tighten on re assembling new drive disc. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
https://www.youtube.com/watch?v=Nz0yykNk2SM
https://www.youtube.com/watch?v=SBrNyGVnkqY
https://www.youtube.com/watch?v=L-yK0JE41Pw