The eight rotational control engines were mounted off the spacecraft's center of mass around the aft section of the Equipment Module, pointed at 90 degree positions up, down, left and right. These were rated at 25 pounds-force (110 N) thrust and fired in pairs, causing it to pitch, roll, or yaw to control attitude.
Six of the translational control engines were mounted on the side of the Retrorocket Module, near the spacecraft's center of mass. Four of these were rated at 100 pounds-force (440 N) thrust, one each pointed up, down, left or right. The other two were pointed forward, at the three o'clock and nine o'clock positions, to provide aft thrust. These were rated at 85 pounds-force (380 N) (reduced from the original spec of 100 pounds-force (440 N) in July 1962).
The two 100-pound-force (440 N) thrust forward translation control engines were mounted on the inside of the aft end of the equipment adapter, at the twelve o'clock and six o'clock positions.
During Gemini 8, on March 16, 1966, OAMS engine number 8 became stuck on, resulting in uncontrollable spinning of the spacecraft. The entire OAMS had to be shut down and the mission was terminated prematurely. This resulted in modifications to OAMS to permit engine isolation.