Just a crazy out there thought if you don't have worn parts. Does you engine spin down very fast after backing off due to really high compression? The reason I ask is potentially your power steering pump is no longer spinning fast enough to counter the torque. Kind of like one of the earlier threads mentioned about the blades are now acting like a rudder. I guess the big test for this is:

1. If it happens without a big jerk on the wheel then worn parts.

2. If your wheel is fighting back really hard and you can correct with steering input that seems hard then maybe P/S pump pressure issue.

Most likely worn parts though and the external add-on system is pretty easy to install and works nicely.

Thanks found the gimbal ring bad just ordered new thanks for info.