An actuator assembly having an actuator block, at least one elongated arm, and an expandable key for attaching the elongated arm to the actuator block. The actuator block has a connection hole formed in the block, the hole having a perimeter edge of predetermined shape. A corresponding connection hole having a perimeter edge of predetermined shape is formed in the elongated arm. The expandable key is inserted in the actuator block connection hole and the elongated arm connection hole and is transversely expanded to engage the perimeter edges of the holes. The expandable key includes a key member having a longitudinal bore. The key member is inserted through the actuator block connection hole and the elongated arm connection hole, and a driver pin is inserted in the longitudinal bore of the key member. The driver pin contacts and transversely expands the key member, thus causing the key member to engage the perimeter edges of the connection holes to secure the elongated arm to the actuator block. A plurality of elongated arms can be attached to the actuator block in this manner, and the driver pin and key member can be removed for selectively reworking and replacing one or more of the plurality of elongated arms.