Teach your wife/girlfriend to keep the aircraft S&L in the cruise and fly the interesting bits yourself, it's got to be cheaper than fixing this 60's technology and there is probably less chance of her rolling the aircraft on its back !
My wife (PPL/IMC) and I fly together and we have rewritten the checklist - to cover several items such as familiarisation with the AP CB and all the ways to disconnect in the event of a trim runaway. I fly with my left thumb permanently covering the AP disconnect (BD Altimatic V) although in 2000+ hours it has worked without incident.
This made chilling reading - H&W team flying a 182 fitted with a KAP 140 and an inadvertent autopilot engagement in altitude hold mode before takeoff.
http://www.aaib.gov.uk/cms_resources...pdf_501522.pdf
I have no personal experience of an S TEC AP.