Cardiffstag

Hi guys, Im new to the forum. I have had this Smartech Nitro car for about 5 years but only used it for the 1st 1 or 2 months. 2days ago I found it in my garage wiped the dust off and had a quick look under the shell.

I don't know anything about these cars at all so I have one or two questions.
1, I can start the car but the wheels never stop moving, Once I put it on the floor it cuts out?

2, The 2 right wheels move but the 2 left ones don't, Why is this?

3, I don't have the instructions anymore and there are a few settings on the controller but I don't know what they all do. The slider on the right moves up and down and controlls the throttle but the car won't go flat out unless the slider is all the way to the top but then the car won't stop unless I bring the slider down again. Is this normal?

Any Help would be great, Not sure if the car has had it's days or what.

Thanks in advance.