27Mhz/40Mhz Radio control for model cars
 

My little son has two radio controlled model cars from Company Tronic
toys.
Since a couple of weeks I have the problem that the range of the radio
control of one car is getting shorter and the radio control of the
other car sometimes shows a malfunction, i.e. instead of driving to
the right side it drives to the left or backwards and so on.
The company Tronic toys does not exist anymore and therefore there is
no support available and on the other hand I don't want to throw away
both cars.
Since I'm familiar with electronics I hoped to repair both cars but
unfortunately I'm not experienced in radio control.
So maybe there is somebody who could give me some support in kind of
schematics, principle scetches or simple hints.

Thanks in advance !

Dieter