Try this link on you tube
Our directions were very small too but I have put together the plasmacar and the swivel car. Both are very easy. Just make sure the back wheels are in the correct position as shown in the video. If this link doesn't work just search for "plasma car instructions" and you will find plenty to choose from. Good luck! The kids love them!
I am not sure of who the manufacture is. That is who I think would be the one to provide replacement parts. Mine did not come with much information, like a booklet or anything, but maybe you have yours and could try to google the manufacture. Thanks for asking!