I was going to suggest, at a point in the thread, a piece of clear plexiglass to replace the top cover to allow a visual while the lathe was running.
This thread has been of great interest to me as I have some noise issues since replacing the motor with a VFD driven one on my Grizzly G0602 lathe. I've suspected the VFD from the git go but still haven't figured out if its that or the spindle bearings. May have to take another look at parameter settings.
Sure glad you got your new lathe up and running! Enjoy!