CHALLENGER HELP!!

Have just bought the challenger system and spent 2 hrs last night trying to get it to run consistently. I am running it on a 17m classic track with sport power and have checked that power is consistent all the way round. It did work last night a few times correctly but the problem is that is does the two learning circuits and then when the car parks just past the magnet, it just shows one light on one side that stays on? ( There is nothing in the instructions for one light staying on?) Then if you press fast or slow the gantry starts from red and then just goes to both green lights and the car does not move......

Now if i place the car behind the start it moves up as it should to the start and flashes correctly ready to go - press slow (or fast) and it then just launches itself like a missile down my long straight flat and tries to go round my rad2 bend flat out with spectacular air borne results

I have placed all the controls in the middle of my 12 ft straight so they are away from all the bends and i have altered the track slightly removing crossovers and chicanes - I did this as when it ran correctly a few times it struggled on these parts

I am at a loss and will test it tonight on a simple small oval - if that fails i will return it to Scalextric - I am new to this site and thought i would try some experts!

Thanks in advance