Since owning our Sabre since summer 2012, I've found that the base of the rolling island takes a lot of bouncing while traveling feet down in the rear.
Our bottom panel on island was settling, causing the castor feet difficulty in turning and flipping tabs to lock down wheels...so I realigned the wood floor, wood screw back in place & placed spacers between wheels.
You can avoid this problem by storing island table top down but way inconvenient when you ise the cabinet for food storage so we choose to store deet down...just be prepared for the island floor adjusting (mostly staples in this area & not screws!)
Limited wheel gap before repair...
New wheel gap after repair