The oversize extractor used in the E series guns has a couple of different extractor springs available, as I recall. I'd have to look for the list I got when I was ordering some parts last year (in preparation of thinking about adding one sometime). I just remember realizing at the time that the springs and extractor pin were different for the E series guns than for my regular SW1911 5" gun.
Also, the extractor tension isn't checked by seeing whether it holds a Dummy round when the slide is gently shaken. The external extractor fit is checked differently (bar gauge) than an internal "1911" extractor, as is the tension (force dial gauge).
I'd have company check the gun again. There's no reason they can't get the PC style oversize .45 extractor to run well in the E series guns.
Might be something other than just the extractor or its tension, too.
FWIW, if I were function-testing a repaired 1911, I'd choose to use factory ammunition that runs more toward the upper end of the normal power levels for 230gr ball or hollowpoint loads.