I have a Sega Super GT twin cab. When I received it, the force feedback in the left cab was not functioning. After some part swapping and a new power cord, both sides have force feedback functioning.
However, the right cab has stronger resistance turning right than turning left. This causes the wheel to move sharply to the left at the beginning of any race, and makes the game near impossible to play.
There are no Drive Board Errors, and the Drive Board Tests are clean -- the wheel registers all movement correctly. I've used the test to confirm the resistance difference between roll left and roll right.
The Drive Control Board has dip switches 3 and 4 flipped on for both cabs. I'm planning to fiddle with those next, although the manual I have isn't clear on the proper setting.