It looks like you are mixing Scalextric Classic and Sport track.
This is not a problem but you have to check the guide blade depth: Newer cars have deeper guide blades and will "bottom out" on the classic track.
Also I see you have the C7042 digital pwoer base. Running digital is great fun but requires perfect conductivity all around.
Older classic track is often prone to drop outs.
You have to keep it in pristine condition and maybe use jumper cables: