That is not something you want to be fooling around with. Besides the fact it could be a very dangerous system, we don't know enough about them yet to have a history. They could prove to be as safe as sitting on 100 pounds of dynamite, (a tank of gasoline), or they could prove to be in the news like the Toyotas of two years ago. If anything happens to lead to a crash and a lawyer or insurance investigator finds out you worked on this system, you will be a potential party to any lawsuit, even if it had nothing to do with that crash. Lawyers are real good at twisting things around to convince juries their client is not totally at fault.
If you still want to try to work on this assembly, you're going to find no parts are available from the manufacturer. They have their bases covered as far as liability. They know all the adjustments and tests because they designed it. If you look back at GM's very nice HEI distributor, any of their generators with built-in voltage regulators, and wheel bearings with built-in anti-lock brake wheel speed sensors, they like to supply assemblies, not repair parts, whenever practical. Other manufacturers are going the same way.
My recommendation is to forget repairing any throttle-by-wire assembly and just appreciate the fact that parts are more expensive but repair times are much shorter.