I am periodically having many of the problems previously described during a thread that covers 10 months.  But I see no solution to any of them:

1)  AP NAVLOC ON  VOR captured (green light is ON) flying properly to the heading - ALT HOLD & ELEV engagement switch is OFF is off but AC climbs at 1000'/minute even with maximum down yoke/down trim.  Turn off AP and I immediately regain elevator control.    As soon as I engage AP-NAV LOC the AC starts climbing

2) AC & AP are working perfectly - AC is stable in NAV-LOC with ALT HOLD on.  FL 20 at Mach .71  - suddenly the AC starts falling from sky at 5,000 fpm while maintining Mach.71 and N1 at ~85%.   IAS starts to drop rapidly, I push over, increase the throttle to 99% but the IAS continues to drop and the Vertical Airspeed does not change.  If I push over into a near vertical dive the flight ends with a an Overspeed/Overstress and IAS of less than 100 kts just before breakup.  

When this happens at 9,000' and 225 kts there is no way to recover.  The AC pancakes at a vertical speed of 6000 fpm and IAS of 0 kts with N1 at 100%.

3) AC is on AP (NavLoc/Alt Hold) and stable at Mach .71 - starts going up and down 1000 fpm in a slow fashion - throttles don't move, control surfaces don't move but plane climbs then descends.  Turning off AP immediately stabilizes AC.

4) Level Stable flight at 15,000  Nav1 captures VOR - I hear the correct  Morse Code - AP on NavLoc - green light on dash - Aileron and Elevator engaged in AP   The DME is showing the correct distance and the HSI is lined up with the correct course selected.  BUT - - AC flys at right angels or even away from VOR.  

Most of the time (over 80% of flight hours) the AP works just as it should.  :D

I know it's an old AP but is that the way it is supposed to work?