Honestly if you have facebook there is a modified power wheels group that is much more active and has parts listing and more information.

Personal opinion but when you get to the range of 775's and metal gears you're better off getting a small atv or go cart. like this https://www.amazon.com/Razor-Electric-Four-Wheeled-Off-Road-Vehicle/dp/B00H4PDXAS/ref=sr_1_39?keywords=electric+go+kart&qid=1684360466&sprefix=electric+go%2Caps%2C80&sr=8-39

You'll invest half the cost for less reliability, and less speed