So today I drove my 4x4 slash for the 4th time. I have a brand new venom 7.4v 5000mah lipo battery for it so it goes very fast. My allen loosened on my pinion gear and slide off so it wasn't catching. So, I watched a youtube video and tore into it and got it back lined up after taking the whole rear end off which i didn't need to do. I drove it again with the battery not fully charged but enough. It was very slow compared to normal. I firgured it was the battery but I ended up getting 15-20 min out of my battery. So whats wrong now then?