Tesla is so secretive that nobody outside really has a clue what the problems are. Even the automotive trade press doesn't know. There are so many possibilities. As I wrote last time this came up, Tesla would probably be better off letting some competent automotive reporters tour the plant. Right now, investors are assuming the worst.

What's surprising is that Tesla is also having trouble with battery pack manufacturing. That's far simpler than building a car. It's a good job for robots, building identical units made of a large number of the same components.