Technical check every thing!

There is a stratum in the market where it is possible to make parts cheap enough that most people will simply throw them away after having sworn at them for a few minutes. Their manufacturers have enough people they can sell a part to once. I picked up a cheap door handle for my DD, brand new, out of the box. I was willing to forego a bit of delicacy of finish for that price. I was also expecting a bit of t*******, filing, etc. to be necessary to get it to work properly. I was not expecting it not to work at all, not even almost to work, not vaguely even to fit the holes in the door.

It's obvious that the manufacturer never intended it to work. They make their money purely by the thing being too cheap for most people to make a fuss about.

 

I like buying parts at the junkyard from wrecked cars. That way I figure that the part was "working when wrecked".
I went through several alternators from a chain parts store. When I got tired of testing them for them by installing them on my vehicle I made them test the latest one on their machine in the store before accepting it. That has now become my standard policy on anything with a wire on it.