RTV 1100 steering locks

[rd_macgregor]

Have a 2009 RTV 1100 (diesel, full cab, hydraulic dump, power steering) bought last month and, among other issues, it sometimes suffers a steering lock up. Worst is a sharp left turn, then when straightening out, it will suddenly lock in position...when (panicked!!) I let off the fuel, the lock-up releases.
While driving straight, I can feel a slight bump, or catch, in the steering (right at the wheel position where the lock-up occurs) if I swerve left or right a bit. Any suggestions as to what might be causing this issue?
Thanks.