The electronics on WLToys vehicles are junk. The ESC (electronic speed control), servo driver and receiver are all one unit. If one function goes out, you have to replace the whole thing. Likewise, the transmitter is not very reliable. So, most owners buy a new transmitter and reciver, a 3-wire servo and a brushed ESC - all separate components.
Components most often used can be found here:
https://www.rcgroups.com/forums/show...428-MOD-Thread