FWIW my neighbor just received a new grizzly. Impressive fit and finish - was in the $2,000 ballpark for cost. BIG disappointment when fired up - rumbling/rattling metal handles. Never would pass the old "stand a nickel on edge while it's running" test.
Opened side door and saw the triple drive belts are likely the cause- regardless of how much you torqued, they are flapping willy - nilly in there. I suggested he go buy a matched set of quality V belts to help tame this, but he's not as fussy as I...
I've had a humble little Jet supersaw for 12 years now. Though I long for more power, it uses a micro-V drive belt, and to this day runs super smooth. NO comparison to the new Griz. Sorry to grizzly, as I've got many of their machines, most I'm very fond of performance to dollar investment, but after this I have no interest in their table saws.
One last interjection- Just bought a new drill press this week - Jet JDP-17. Very well tuned for the woodworker. Thought I'd mention, as it too employs a micro-V drive which contributes to super-smooth operation. Many more extras like t-slots and removable insert plate w/levelers in the cast work table. LED work light and laser cross hairs actually are pro-grade, well done and not like the cheesy- cheap do-all copies out there. Final icing on the cake: 5" quill travel - woohoo!!!
jeff