I have just completed fitting the chip to the locomotive. 4 screws are used to attach the chassis to the body. These are removed first. I then disconnected the brake pipes at the front and rear. The body and chassis now separate. I disconnected the four cable plug from the chassis. Body and chassis are now fully separated. The pcb to which the chip is fitted is located in the body. I carefully removed it from its 2 guides and fitted the chip directly to it. There is only way that the chip fits into the pins. The only thing to watch out for is the lead to the front power socket getting in the way odf the pcb when you refit the pcb back into its guides. I then reconnected the four cable plug back into its socket on the chassis. This was followed by refitting the 2 brake pipes, front and rear. Finally I fitted the 4 screws that lock the body to the chassis.