Actually a part such as you are dealing with here "may not have" changed much since.........1970!!!!
"Rebuilds" AKA carbs, starters, generators / alternators etc etc etc have ALWAYS had a somewhat poor reputation. They have NEVER had any labor allowance for defectives, that is, if you are a line mechanic, installing what turns out to be a defective booster, YOU get to take it back off on "your own time." It's been that way as long as I remember.
The big difference "now" insofar as "our cars" go, is that NOW you cannot make the choice (often) between replacement new and rebuilt parts.
I know of NO auto parts rebuilder that is head and shoulders above "the rest" in quality / reputation.
