Ok, I've adjusted rumble filter, extension, and damping settings. The only real difference was with rumble on the low bass was actually louder but it didn't affect the dip.
I moved the speaker (only working with the left speaker at this point) up to 6" into the room, 6"closer to the front wall, 6" closer to the center, and 6" closer to the side wall.
I adjusted toe in incrementally until the speaker almost faced the side wall and crossed in front of the LP like a horn.
I also tried removing the diffraction/absorption (GIK Alpha panel) at the first reflection point.
The only thing I really managed to do was turn the dip into a bi-modal dip at 125Hz and 175Hz.