Why would the power door locks on a 1990 Nissan 300ZX not lock anymore?

In my sons 1993 300zx there is an electric accuator located behind the door handle, his was broken, need to remove door panel to acsess. In my 300zx, there are 2 cheap plastic black pieces connecting a set of 2 metal rods (one going to the back of the door and one going into the door handle/power) You have to disassemble the door to get to it, try replacing that if it's broken or not even there.