Update
After spending All day with Brisbane boys and they found theres nothing wrong with my electric speedo gears. It was my speedo dash 3 caps that needed replacing ($5)
Now my speedo reads spot on.
If you have similar problem as mine.
Watch this YouTube, it explains how to fix / replace caps.
https://www.youtube.com/watch?v=G7qzfjwzT14Lucky I didnt go back to Toyota and fork out $600 for the speedo gears. Tbh they dont know what theyre doing, only guessing.
So a big thank you to these lovely Brisbane boys and nice meeting you all :-)