What was found
ENROUTE, IN CRUISE FLIGHT, THERE WAS A SUDDEN AND INADVERTENT PITCH UP AND ROLL OF ACFT, WHILE TRYING TO RECOVER, UNUSUAL ATTITUDE ACFT PITCH AND ROLL CONTINUED INADVERTENTLY. THE CO-PILOTS VGI HAD NOT TUMBLED AT THAT POINT AND WAS INDICATING THE UNUSUAL ATTITUDES. SECURED THE PRIMARY SERVOS WITH NO AFFECT THEN ISOLATED THE AUXILIARY SERVOS AND AFCS. ACFT BECAME CONTROLLABLE AND DIVERTED. REMOVED SUSPECTED MALFUNCTIONING COPILOT PITCH AND ROLL GYRO, PN 121672-01-17, SN 0000450. INSTALLED SERVICEABLE COPILOT PITCH AND ROLL GYRO PN 121672-01-17, SN 0000507 IAW S61 MM, CH 22-10-18 PG 201. OPS CHECK GOOD.