What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS INTERMITTENT AUTOPILOT PITCH MOVEMENT TWITCHING IN SMOOTH LEVEL FLIGHT. NOTE: UPON DESCENT FD BARS & AIRCRAFT (GOLD TRIANGLE SYMBOL) STAYED TOGETHER BUT PITCHED UP & DOWN RELATIVE TO THE HORIZON AND AUTOPILOT FOLLOWED THIS INSTRUMENT MOVEMENT ON CA PFD ONLY AUTOPILOT WAS CONNECTED TO F.O. SIDE AND ALTHOUGH AUTOPILOT PITCH WAS OSCILLATING THE F/O/ PFD WAS STABLE. MAINTENANCE FOUND MULTIPLE ATTITUDE 1 SIGNAL FAULTS ON BOTH DFGCS DURING FAULT REVIEW. REPLACED THE #1 VERTICAL GYRO IAW AMM 34-23-01. OPS TEST GOOD.