ACFT EQUIP PROB. VERT GYROSCOPE CAUSING AUTOPLT OSCILLATION.

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IN THE EARLY PORTION OF OUR ARR DSCNT; THE CTL COLUMN MOVED AFT ABRUPTLY 1 1/2 INCHES OR LESS WITH NO CORRESPONDING PITCH UP MOTION OF THE ACFT. THE CTL COLUMN HAD ALSO MOVED IN THE ROLL MOTION 1/2 INCH WITH NO ACFT ROLL. BOTH OCCURRED WITH AUTOPLT 'A' IN USE. THE PITCH MOTION WAS MORE NOTICEABLE AND THOUGH OTHERS HAVE EXPERIENCED THIS AND A VERT GYROSCOPE WAS USUALLY AT FAULT; I DIDN'T BELIEVE EITHER MOTION WAS PRONOUNCED ENOUGH AND BECAUSE OF THE PITCH AND NO COMMANDED ROLL OR YAW OCCURRED; I DID NOT PROPERLY DIAGNOSE THE SIT. IN LIGHT OF PREVIOUS B737 AUTOPLT RELATED UNCOMMANDED ROLLS AND YAWS; I SHOULD HAVE TRIED THE VERT GYROSCOPE 'CAPT ON AUX' SETTING ON THE SELECTOR KNOB; AND THEREFORE I WOULD HAVE ELIMINATED THE REMOTE POSSIBILITY OF AN UNCOMMANDED ROLL/YAW IF THE TWO HAD BEEN RELATED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SAYS THE PRIMARY FOCUS OF SUBMITTING THE RPT WAS A RESULT OF THE EXTRA ATTENTION GIVEN TO THE B737-200 CONTROLLABILITY QUESTIONS. THE CTL COLUMN MOVEMENT WAS NOT EXTREME; BUT RPTR THOUGHT IT WAS MORE MOVEMENT THAN USUAL. HE SUSPECTED THE VERT GYROSCOPE WAS CAUSING THE EXCESS MOVEMENT AND SAYS THAT HE SHOULD HAVE CHKED THE AUTOPLT OPS ON THE AUX GYROSCOPE. FEEDBACK FROM HIS COMPANY WAS THAT IT WAS NON-EVENT; BUT THANKED HIM FOR THE RPT.