Oh I have to share what just happened! My husband’s power wheelchair suddenly wouldn’t drive. In tilt mode it would still tilt, but in the driving modes it had an error message. By asking in forums he learned that message could mean it thought it was tilted back too much for safe driving, even though it was fully upright. So he tilted way back, and I looked underneath for anything loose, finally tightened one loose screw that I frankly think was unrelated. Then he tilted upright again, giving it an extra couple seconds of push on the joystick, and I pushed forward on the back of the chair. Nothing moved, it was already fully upright. But it did the trick! It’s driving fine now.