Thank you so much for taking the time to chime in. This is exactly what I was hoping to hear from someone who has a deep understanding of Garrard.
The turntable and tonearm was professionally installed by my dealer. We went whole nine yards so I am ruling out bullet 2 and 3. Removing subs helped but not a long term solution, that’s why I am now using a phono with subsonic filter.
I would look into bullet 4 once I consult with my dealer (he is in Nashville too). My Garrard was completely rebuilt by Audio Grail, UK so I suspect it’s the motor but external PSU is definitely worth pursuing (and I will eventually).
Bullets 6-7 are in play this weekend as I am going to pull out my 800 plus lbs, Core Audio quad rack from storage and re-configure my system. Being on suspended floor + subs are not the best condition for turntable. Let’s see if changing out racks helps with chassis born vibrations.