In post # 1 you state that you got a Trailmaster Blazer. I am assuming trailmaster
is the brand name and blazer is the model, and this kart was purchased brand new. I only ask this to establish a warning to other prospective buyers. I truly feel sorry for you that you received such a LEMON. Inexcusable to let something so shody and poorly put together out the door. I am used to crapy stuff from China.
I own 4 two seaters. 3 of them are old refurbished American built and one is a little more modern ( 2006 ) Chinese built. I even own a 2020 Trailmaster 200 mini bike. All powered by Chinese engines. Never seen anything as bad as you got. Was it heavily discounted? I think I would have raised some hell with the vendor.
FWIW I bought my mini bike from Go Power Sports. Not necessarily the lowest price, but have been reputable and shown good customer service to me. I have purchased at least 25 times from them over the last 4 years. I hope that the rest of your kart goes smoothly. Frustrating with the kids waiting.