Paul, I have encountered the same problem and found that the user's asymmetric sitting position was a factor, exaggerated by the fact that the powerchair had a raise and tilt facility causing the whole seat to list slightly to one side. I am in the process of trying the new DX mini joystick as a chin control. Gary Williams Rehab. Eng. Wirral wheelchair centre St. Catherines hospital Derby Rd. Birkenhead Merseyside CH41 0LQ Tel 0151 604 7261 or 07733 225606 e-mail [log in to unmask]