To the best of my knowledge, the pressing plant also did the cut.
Too late for this time, but for future reference-- I recommend never leaving things like mastering or even metal finishing up to chance, or to "staff." Far, far too important.
2. The track at the end of side A (the one with the most noise) is literally the first half of the track at the end of side B (no noise). both halves were recorded as one song, same instruments, mixed as one song, but split up to make room on the sides. if the source that i provided was the issue (as they are claiming), wouldn't the sibilance on side A also be present on side B?
Not necessarily, particularly if the person who did the cut isn't as skilled at dealing with the different requirements of inner diameter vs. outer diameter. To my understanding, it's easier to cut challenging program material on the outer diameter than the inner diameter.
Since the record rotates at a constant number of revolutions per minute, and since the outer diameter is much larger than the inner diameter, the stylus literally moves faster across the outer perimeter, and slower on the inner perimeter. This means that any "squiggles" in the outer diameter are bigger, and less scrunched-together (to use a scientific term). I'm not a cutting engineer, so Paul or someone can correct me if I'm wrong, but I believe distortion can becaused on the inner diameters by cutting or tracing losses-- cutting loss being "the squiggle is so narrow that trailing edge of the cutterhead wipes away or distorts what the leading edge just cut", and tracing losses being "the fancy cutterhead can make the squiggles, but your consumer playback stylus can't accurately follow their complex contours."