I flew two Seneca Five twins an earlier King autopilot equipt aircraft and a later S tech autopilot equipt aircraft.
We had no end of problems with the S tech.
Lock onto an ILS and while the King would fly the needles to almost the ground the S tech would start wallowing all over the place as you got closer in get worse and loose the plot!
An engineer described the S TECH as a load of cheap rubb+sh.
Pace